Polycarbonate polyol compositions and methods

ABSTRACT

In one aspect, the present disclosure encompasses polymerization systems for the copolymerization of CO 2  and epoxides comprising 1) a catalyst including a metal coordination compound having a permanent ligand set and at least one ligand that is a polymerization initiator, and 2) a chain transfer agent having one or more sites capable of initiating copolymerization of epoxides and CO 2 , wherein the chain transfer agent contains one or more masked hydroxyl groups. In a second aspect, the present disclosure encompasses methods for the synthesis of polycarbonate polyols using the inventive polymerization systems. In a third aspect, the present disclosure encompasses polycarbonate polyol compositions characterized in that the polymer chains have a high percentage of —OH end groups, a high percentage of carbonate linkages, and substantially all polycarbonate chains having hydroxyl end groups have no embedded chain transfer agent.

PRIORITY CLAIM

This application is a continuation of U.S. application Ser. No.14/402,835, filed Nov. 21, 2014, now U.S. Pat. No. 9,388,277, which is anational stage application of International Application No.PCT/US2013/042712, filed May 24, 2013, which claims priority to U.S.Application Ser. No. 61/651,254, filed May 24, 2012, the entirety ofeach of which is incorporated herein by reference in its entirety.

BACKGROUND

Polycarbonate polyols are known to have utility as building blocks forthe construction of co-polymers such as flexible urethane foams,urethane coatings, rigid urethane foams, urethane/urea elastomers andplastics, adhesives, polymeric coatings and surfactants among others.Existing commercial polycarbonate polyols fall into two classes, thosewith perfectly alternating structure in which each repeating unit in thepolymer chain contains a carbonate linkage, and those containing amixture of carbonate and ether linkages (more properly called polyetherpolycarbonates). The former are derived from diols such as 1,4 butanediol or 1,6 hexane diol and phosgene (or its equivalent) and have threeor more CH₂ groups between each carbonate linkage, while the latter havea two carbon chain between each carbonate linkage and are typically madefrom epoxides and CO₂ using double metal cyanide catalysts. Polyols withtwo carbon atoms separating the carbonate linkages and having aperfectly alternating structure are not available commercially. Polyolsderived from epoxides and CO₂ and having a perfectly alternatingstructure have only recently been made and are described in WO2010/028362. Examples of such polyols include poly(propylene carbonate)(PPC); poly(ethylene carbonate) (PEC); poly(butylene carbonate) (PBC);and poly(cyclohexene carbonate) (PCHC) as well as copolymers of two ormore of these.

To have utility in these applications, it is preferable that allpolycarbonate polymer chain ends terminate with hydroxyl groups. Suchhydroxyl groups serve as reactive moieties for cross-linking reactionsor act as sites on which other blocks of a co-polymer can beconstructed. It is problematic if a portion of the chain ends on the APCare not hydroxy groups since this results in incomplete cross-linking ortermination of the block copolymer. A typical specification foraliphatic polycarbonate polyol resins for use in such applications isthat at least 98% or in some cases greater than 99% of chain endsterminate in hydroxyl groups. In addition, these applications typicallycall for relatively low molecular weight oligomers (e.g. polymers havingaverage molecular weight numbers (M_(n)) between about 500 and about15,000 g/mol). It is also desirable that the polyols have a narrowlydefined molecular weight distribution—for example, a polydispersityindex less than about 2 is desirable, but much narrower distributions(i.e. PDI<1.2) can be advantageous. Furthermore, for certainapplications, polyol polycarbonates having little or no contaminationwith ether linkages are desirable. Although progress has been maderecently employing particular catalysts along with chain transferagents, new advances in producing polycarbonate polyols having a highpercentage of —OH end groups are needed.

SUMMARY OF THE INVENTION

In one aspect, the present disclosure encompasses polymerization systemsfor the copolymerization of CO₂ and epoxides comprising 1) a metalcomplex, and 2) a chain transfer agent having one or more sites capableof initiating copolymerization of epoxides and CO₂, wherein the chaintransfer agent contains one or more masked hydroxyl groups.

In some embodiments, the present disclosure encompasses methods for thesynthesis of polycarbonate polyols. In some embodiments, a methodincludes the steps of:

-   -   a) contacting a reaction mixture comprising one or more epoxides        with a polymerization system described herein in the presence of        carbon dioxide;    -   b) allowing the polymerization reaction to proceed until a        desired molecular weight aliphatic polycarbonate polyol has        formed,    -   c) terminating the polymerization; and    -   d) treating the aliphatic polycarbonate polyol under suitable        conditions to unmask the one or more masked hydroxyl groups,        wherein the one or more masked hydroxyl groups are hydroxyl        protecting groups or latent hydroxyl groups.

In some embodiments the method further includes contacting the reactionmixture with a co-catalyst.

In some embodiments, the present disclosure encompasses polycarbonatepolyol compositions characterized in that polymer chains have a highpercentage of —OH end groups and wherein substantially all polycarbonatechains having hydroxyl end groups have no embedded chain transfer agent.

The present disclosure further provides, among other things,polyurethane compositions formed by reacting one or more isocyanateswith a provided polycarbonate polyol. In addition, the presentdisclosure encompasses articles of manufacture comprising providedpolyols or polyurethanes.

DEFINITIONS

Definitions of specific functional groups and chemical terms aredescribed in more detail below. For purposes of this invention, thechemical elements are identified in accordance with the Periodic Tableof the Elements, CAS version, Handbook of Chemistry and Physics, 75^(th)Ed., inside cover, and specific functional groups are generally definedas described therein. Additionally, general principles of organicchemistry, as well as specific functional moieties and reactivity, aredescribed in Organic Chemistry, Thomas Sorrell, University ScienceBooks, Sausalito, 1999; Smith and March March's Advanced OrganicChemistry, 5^(th) Edition, John Wiley & Sons, Inc., New York, 2001;Larock, Comprehensive Organic Transformations, VCH Publishers, Inc., NewYork, 1989; Carruthers, Some Modern Methods of Organic Synthesis, 3^(rd)Edition, Cambridge University Press, Cambridge, 1987; the entirecontents of each of which are incorporated herein by reference.

Certain compounds of the present invention can comprise one or moreasymmetric centers, and thus can exist in various stereoisomeric forms,e.g., enantiomers and/or diastereomers. Thus, inventive compounds andcompositions thereof may be in the form of an individual enantiomer,diastereomer or geometric isomer, or may be in the form of a mixture ofstereoisomers. In certain embodiments, the compounds of the inventionare enantiopure compounds. In certain other embodiments, mixtures ofenantiomers or diastereomers are provided.

Furthermore, certain compounds, as described herein may have one or moredouble bonds that can exist as either the Z or E isomer, unlessotherwise indicated. The invention additionally encompasses thecompounds as individual isomers substantially free of other isomers andalternatively, as mixtures of various isomers, e.g., racemic mixtures ofenantiomers. In addition to the above-mentioned compounds per se, thisinvention also encompasses compositions comprising one or morecompounds.

As used herein, the term “isomers” includes any and all geometricisomers and stereoisomers. For example, “isomers” include cis- andtrans-isomers, E- and Z-isomers, R- and S-enantiomers, diastereomers,(D)-isomers, (L)-isomers, racemic mixtures thereof, and other mixturesthereof, as falling within the scope of the invention. For instance, astereoisomer may, in some embodiments, be provided substantially free ofone or more corresponding stereoisomers, and may also be referred to as“stereochemically enriched.”

Where a particular enantiomer is preferred, it may, in some embodimentsbe provided substantially free of the opposite enantiomer, and may alsobe referred to as “optically enriched.” “Optically enriched,” as usedherein, means that the compound is made up of a significantly greaterproportion of one enantiomer. In certain embodiments the compound ismade up of at least about 90% by weight of a preferred enantiomer. Inother embodiments the compound is made up of at least about 95%, 98%, or99% by weight of a preferred enantiomer. Preferred enantiomers may beisolated from racemic mixtures by any method known to those skilled inthe art, including chiral high pressure liquid chromatography (HPLC) andthe formation and crystallization of chiral salts or prepared byasymmetric syntheses. See, for example, Jacques, et al., Enantiomers,Racemates and Resolutions (Wiley Interscience, New York, 1981); Wilen,S. H., et al., Tetrahedron 33:2725 (1977); Eliel, E. L. Stereochemistryof Carbon Compounds (McGraw-Hill, NY, 1962); Wilen, S. H. Tables ofResolving Agents and Optical Resolutions p. 268 (E. L. Eliel, Ed., Univ.of Notre Dame Press, Notre Dame, Ind. 1972).

The terms “halo” and “halogen” as used herein refer to an atom selectedfrom fluorine (fluoro, —F), chlorine (chloro, —Cl), bromine (bromo,—Br), and iodine (iodo, —I).

The term “aliphatic” or “aliphatic group”, as used herein, denotes ahydrocarbon moiety that may be straight-chain (i.e., unbranched),branched, or cyclic (including fused, bridging, and spiro-fusedpolycyclic) and may be completely saturated or may contain one or moreunits of unsaturation, but which is not aromatic. Unless otherwisespecified, aliphatic groups contain 1-30 carbon atoms. In certainembodiments, aliphatic groups contain 1-12 carbon atoms. In certainembodiments, aliphatic groups contain 1-8 carbon atoms. In certainembodiments, aliphatic groups contain 1-6 carbon atoms. In someembodiments, aliphatic groups contain 1-5 carbon atoms, in someembodiments, aliphatic groups contain 1-4 carbon atoms, in yet otherembodiments aliphatic groups contain 1-3 carbon atoms, and in yet otherembodiments aliphatic groups contain 1 or 2 carbon atoms. Suitablealiphatic groups include, but are not limited to, linear or branched,alkyl, alkenyl, and alkynyl groups, and hybrids thereof such as(cycloalkyl)alkyl, (cycloalkenyl)alkyl or (cycloalkyl)alkenyl.

The term “unsaturated”, as used herein, means that a moiety has one ormore double or triple bonds.

The terms “cycloaliphatic”, “carbocycle”, or “carbocyclic”, used aloneor as part of a larger moiety, refer to a saturated or partiallyunsaturated cyclic aliphatic monocyclic or polycyclic ring systems, asdescribed herein, having from 3 to 12 members, wherein the aliphaticring system is optionally substituted as defined above and describedherein. Cycloaliphatic groups include, without limitation, cyclopropyl,cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl,cycloheptyl, cycloheptenyl, cyclooctyl, cyclooctenyl, norbornyl,adamantyl, and cyclooctadienyl. In some embodiments, the cycloalkyl has3-6 carbons. The terms “cycloaliphatic”, “carbocycle” or “carbocyclic”also include aliphatic rings that are fused to one or more aromatic ornonaromatic rings, such as decahydronaphthyl or tetrahydronaphthyl,where the radical or point of attachment is on the aliphatic ring. Incertain embodiments, the term “3- to 8-membered carbocycle” refers to a3- to 8-membered saturated or partially unsaturated monocycliccarbocyclic ring. In certain embodiments, the terms “3- to 14-memberedcarbocycle” and “C₃₋₁₄ carbocycle” refer to a 3- to 8-membered saturatedor partially unsaturated monocyclic carbocyclic ring, or a 7- to14-membered saturated or partially unsaturated polycyclic carbocyclicring. In certain embodiments, the term “C₃₋₂₀ carbocycle” refers to a 3-to 8-membered saturated or partially unsaturated monocyclic carbocyclicring, or a 7- to 20-membered saturated or partially unsaturatedpolycyclic carbocyclic ring.

The term “alkyl,” as used herein, refers to saturated, straight- orbranched-chain hydrocarbon radicals derived from an aliphatic moietycontaining between one and six carbon atoms by removal of a singlehydrogen atom. Unless otherwise specified, alkyl groups contain 1-12carbon atoms. In certain embodiments, alkyl groups contain 1-8 carbonatoms. In certain embodiments, alkyl groups contain 1-6 carbon atoms. Insome embodiments, alkyl groups contain 1-5 carbon atoms, in someembodiments, alkyl groups contain 1-4 carbon atoms, in yet otherembodiments alkyl groups contain 1-3 carbon atoms, and in yet otherembodiments alkyl groups contain 1-2 carbon atoms. Examples of alkylradicals include, but are not limited to, methyl, ethyl, n-propyl,isopropyl, n-butyl, iso-butyl, sec-butyl, sec-pentyl, iso-pentyl,tert-butyl, n-pentyl, neopentyl, n-hexyl, sec-hexyl, n-heptyl, n-octyl,n-decyl, n-undecyl, dodecyl, and the like.

The term “alkenyl,” as used herein, denotes a monovalent group derivedfrom a straight- or branched-chain aliphatic moiety having at least onecarbon-carbon double bond by the removal of a single hydrogen atom.Unless otherwise specified, alkenyl groups contain 2-12 carbon atoms. Incertain embodiments, alkenyl groups contain 2-8 carbon atoms. In certainembodiments, alkenyl groups contain 2-6 carbon atoms. In someembodiments, alkenyl groups contain 2-5 carbon atoms, in someembodiments, alkenyl groups contain 2-4 carbon atoms, in yet otherembodiments alkenyl groups contain 2-3 carbon atoms, and in yet otherembodiments alkenyl groups contain 2 carbon atoms. Alkenyl groupsinclude, for example, ethenyl, propenyl, butenyl, 1-methyl-2-buten-1-yl,and the like.

The term “alkynyl,” as used herein, refers to a monovalent group derivedfrom a straight- or branched-chain aliphatic moiety having at least onecarbon-carbon triple bond by the removal of a single hydrogen atom.Unless otherwise specified, alkynyl groups contain 2-12 carbon atoms. Incertain embodiments, alkynyl groups contain 2-8 carbon atoms. In certainembodiments, alkynyl groups contain 2-6 carbon atoms. In someembodiments, alkynyl groups contain 2-5 carbon atoms, in someembodiments, alkynyl groups contain 2-4 carbon atoms, in yet otherembodiments alkynyl groups contain 2-3 carbon atoms, and in yet otherembodiments alkynyl groups contain 2 carbon atoms. Representativealkynyl groups include, but are not limited to, ethynyl, 2-propynyl(propargyl), 1-propynyl, and the like.

The term “aryl” used alone or as part of a larger moiety as in“aralkyl”, “aralkoxy”, or “aryloxyalkyl”, refers to monocyclic andpolycyclic ring systems having a total of five to 20 ring members,wherein at least one ring in the system is aromatic and wherein eachring in the system contains three to twelve ring members. The term“aryl” may be used interchangeably with the term “aryl ring”. In certainembodiments of the present invention, “aryl” refers to an aromatic ringsystem which includes, but is not limited to, phenyl, biphenyl,naphthyl, anthracyl and the like, which may bear one or moresubstituents. Also included within the scope of the term “aryl”, as itis used herein, is a group in which an aromatic ring is fused to one ormore additional rings, such as benzofuranyl, indanyl, phthalimidyl,naphthimidyl, phenantriidinyl, or tetrahydronaphthyl, and the like. Incertain embodiments, the terms “6- to 10-membered aryl” and “C₆₋₁₀ aryl”refer to a phenyl or an 8- to 10-membered polycyclic aryl ring. Incertain embodiments, the term “6- to 12-membered aryl” refers to aphenyl or an 8- to 12-membered polycyclic aryl ring. In certainembodiments, the term “C₆₋₁₄ aryl” refers to a phenyl or an 8- to14-membered polycyclic aryl ring.

The terms “heteroaryl” and “heteroar-”, used alone or as part of alarger moiety, e.g., “heteroaralkyl”, or “heteroaralkoxy”, refer togroups having 5 to 14 ring atoms, preferably 5, 6, or 9 ring atoms;having 6, 10, or 14 π electrons shared in a cyclic array; and having, inaddition to carbon atoms, from one to five heteroatoms. The term“heteroatom” refers to nitrogen, oxygen, or sulfur, and includes anyoxidized form of nitrogen or sulfur, and any quaternized form of a basicnitrogen. Heteroaryl groups include, without limitation, thienyl,furanyl, pyrrolyl, imidazolyl, pyrazolyl, triazolyl, tetrazolyl,oxazolyl, isoxazolyl, oxadiazolyl, thiazolyl, isothiazolyl,thiadiazolyl, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, indolizinyl,purinyl, naphthyridinyl, benzofuranyl and pteridinyl. The terms“heteroaryl” and “heteroar-”, as used herein, also include groups inwhich a heteroaromatic ring is fused to one or more aryl,cycloaliphatic, or heterocyclyl rings, where the radical or point ofattachment is on the heteroaromatic ring. Nonlimiting examples includeindolyl, isoindolyl, benzothienyl, benzofuranyl, dibenzofuranyl,indazolyl, benzimidazolyl, benzthiazolyl, quinolyl, isoquinolyl,cinnolinyl, phthalazinyl, quinazolinyl, quinoxalinyl, 4H-quinolizinyl,carbazolyl, acridinyl, phenazinyl, phenothiazinyl, phenoxazinyl,tetrahydroquinolinyl, tetrahydroisoquinolinyl, andpyrido[2,3-b]-1,4-oxazin-3(4H)-one. A heteroaryl group may be mono- orbicyclic. The term “heteroaryl” may be used interchangeably with theterms “heteroaryl ring”, “heteroaryl group”, or “heteroaromatic”, any ofwhich terms include rings that are optionally substituted. The term“heteroaralkyl” refers to an alkyl group substituted by a heteroaryl,wherein the alkyl and heteroaryl portions independently are optionallysubstituted. In certain embodiments, the term “5- to 10-memberedheteroaryl” refers to a 5- to 6-membered heteroaryl ring having 1 to 3heteroatoms independently selected from nitrogen, oxygen, or sulfur, oran 8- to 10-membered bicyclic heteroaryl ring having 1 to 4 heteroatomsindependently selected from nitrogen, oxygen, or sulfur. In certainembodiments, the term “5- to 12-membered heteroaryl” refers to a 5- to6-membered heteroaryl ring having 1 to 3 heteroatoms independentlyselected from nitrogen, oxygen, or sulfur, or an 8- to 12-memberedbicyclic heteroaryl ring having 1 to 4 heteroatoms independentlyselected from nitrogen, oxygen, or sulfur.

As used herein, the terms “heterocycle”, “heterocyclyl”, “heterocyclicradical”, and “heterocyclic ring” are used interchangeably and refer toa stable 5- to 7-membered monocyclic or 7-14-membered polycyclicheterocyclic moiety that is either saturated or partially unsaturated,and having, in addition to carbon atoms, one or more, preferably one tofour, heteroatoms, as defined above. When used in reference to a ringatom of a heterocycle, the term “nitrogen” includes a substitutednitrogen. As an example, in a saturated or partially unsaturated ringhaving 0-3 heteroatoms selected from oxygen, sulfur or nitrogen, thenitrogen may be N (as in 3,4-dihydro-2H-pyrrolyl), NH (as inpyrrolidinyl), or +NR (as in N-substituted pyrrolidinyl). In someembodiments, the term “3- to 7-membered heterocyclic” refers to a 3- to7-membered saturated or partially unsaturated monocyclic heterocyclicring having 1 to 2 heteroatoms independently selected from nitrogen,oxygen, or sulfur. In some embodiments, the term “3- to 8-memberedheterocycle” refers to a 3- to 8-membered saturated or partiallyunsaturated monocyclic heterocyclic ring having 1 to 2 heteroatomsindependently selected from nitrogen, oxygen, or sulfur. In someembodiments, the term “3- to 12-membered heterocyclic” refers to a 3- to8-membered saturated or partially unsaturated monocyclic heterocyclicring having 1 to 2 heteroatoms independently selected from nitrogen,oxygen, or sulfur, or a 7- to 12-membered saturated or partiallyunsaturated polycyclic heterocyclic ring having 1-3 heteroatomsindependently selected from nitrogen, oxygen, or sulfur. In someembodiments, the term “3- to 14-membered heterocycle” refers to a 3- to8-membered saturated or partially unsaturated monocyclic heterocyclicring having 1 to 2 heteroatoms independently selected from nitrogen,oxygen, or sulfur, or a 7- to 14-membered saturated or partiallyunsaturated polycyclic heterocyclic ring having 1-3 heteroatomsindependently selected from nitrogen, oxygen, or sulfur.

A heterocyclic ring can be attached to its pendant group at anyheteroatom or carbon atom that results in a stable structure and any ofthe ring atoms can be optionally substituted. Examples of such saturatedor partially unsaturated heterocyclic radicals include, withoutlimitation, tetrahydrofuranyl, tetrahydrothienyl, pyrrolidinyl,pyrrolidonyl, piperidinyl, pyrrolinyl, tetrahydroquinolinyl,tetrahydroisoquinolinyl, decahydroquinolinyl, oxazolidinyl, piperazinyl,dioxanyl, dioxolanyl, diazepinyl, oxazepinyl, thiazepinyl, morpholinyl,and quinuclidinyl. The terms “heterocycle”, “heterocyclyl”,“heterocyclyl ring”, “heterocyclic group”, “heterocyclic moiety”, and“heterocyclic radical”, are used interchangeably herein, and alsoinclude groups in which a heterocyclyl ring is fused to one or morearyl, heteroaryl, or cycloaliphatic rings, such as indolinyl,3H-indolyl, chromanyl, phenanthridinyl, or tetrahydroquinolinyl, wherethe radical or point of attachment is on the heterocyclyl ring. Aheterocyclyl group may be mono- or bicyclic. The term“heterocyclylalkyl” refers to an alkyl group substituted by aheterocyclyl, wherein the alkyl and heterocyclyl portions independentlyare optionally substituted.

As used herein, the term “partially unsaturated” refers to a ring moietythat includes at least one double or triple bond. The term “partiallyunsaturated” is intended to encompass rings having multiple sites ofunsaturation, but is not intended to include aryl or heteroarylmoieties, as herein defined.

One of ordinary skill in the art will appreciate that compound andsynthetic methods, as described herein, may utilize a variety ofprotecting groups. By the term “protecting group,” as used herein, it ismeant that a particular functional moiety, e.g., O, S, or N, is maskedor blocked, permitting, if desired, a reaction to be carried outselectively at another reactive site in a multifunctional compound.Suitable protecting groups are well known in the art and include thosedescribed in detail in Protecting Groups in Organic Synthesis, T. W.Greene and P. G. M. Wuts, 3^(rd) edition, John Wiley & Sons, 1999, theentirety of which is incorporated herein by reference. In certainembodiments, a protecting group reacts selectively in good yield to givea protected substrate that is stable to the projected reactions; theprotecting group is preferably selectively removable by readilyavailable, preferably non-toxic reagents that do not attack the otherfunctional groups; the protecting group forms a separable derivative(more preferably without the generation of new stereogenic centers); andthe protecting group will preferably have a minimum of additionalfunctionality to avoid further sites of reaction. As detailed herein,oxygen, sulfur, nitrogen, and carbon protecting groups may be utilized.By way of non-limiting example, hydroxyl protecting groups includemethyl, methoxylmethyl (MOM), methylthiomethyl (MTM), t-butylthiomethyl,(phenyldimethylsilyl)methoxymethyl (SMOM), benzyloxymethyl (BOM),p-methoxybenzyloxymethyl (PMBM), (4-methoxyphenoxy)methyl (p-AOM),guaiacolmethyl (GUM), t-butoxymethyl, 4-pentenyloxymethyl (POM),siloxymethyl, 2-methoxyethoxymethyl (MEM), 2,2,2-trichloroethoxymethyl,bis(2-chloroethoxy)methyl, 2-(trimethyl silyl)ethoxymethyl (SEMOR),tetrahydropyranyl (THP), 3-bromotetrahydropyranyl,tetrahydrothiopyranyl, 1-methoxycyclohexyl, 4-methoxytetrahydropyranyl(MTHP), 4-methoxytetrahydrothiopyranyl, 4-methoxytetrahydrothiopyranylS,S-dioxide, 1-[(2-chloro-4-methyl)phenyl]-4-methoxypiperidin-4-yl(CTMP), 1,4-dioxan-2-yl, tetrahydrofuranyl, tetrahydrothiofuranyl,2,3,3a,4,5,6,7,7a-octahydro-7,8,8-trimethyl-4,7-methanobenzofuran-2-yl,1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, 1-methyl-1-methoxyethyl,1-methyl-1-benzyloxyethyl, 1-methyl-1-benzyloxy-2-fluoroethyl,2,2,2-trichloroethyl, 2-trimethyl silylethyl, 2-(phenylselenyl)ethyl,t-butyl, allyl, p-chlorophenyl, p-methoxyphenyl, 2,4-dinitrophenyl,benzyl, p-methoxybenzyl, 3,4-dimethoxybenzyl, o-nitrobenzyl,p-nitrobenzyl, p-halobenzyl, 2,6-dichlorobenzyl, p-cyanobenzyl,p-phenylbenzyl, 2-picolyl, 4-picolyl, 3-methyl-2-picolyl N-oxido,diphenylmethyl, p,p′-dinitrobenzhydryl, 5-dibenzosuberyl,triphenylmethyl, α-naphthyldiphenylmethyl,p-methoxyphenyldiphenylmethyl, di(p-methoxyphenyl)phenylmethyl,tri(p-methoxyphenyl)methyl, 4-(4′-bromophenacyloxyphenyl)diphenylmethyl,4,4′,4″-tris(4,5-dichlorophthalimidophenyl)methyl,4,4′,4″-tris(levulinoyloxyphenyl)methyl,4,4′,4″-tris(benzoyloxyphenyl)methyl,3-(imidazol-1-yl)bis(4′,4″-dimethoxyphenyl)methyl,1,1-bis(4-methoxyphenyl)-1′-pyrenylmethyl, 9-anthryl,9-(9-phenyl)xanthenyl, 9-(9-phenyl-10-oxo)anthryl,1,3-benzodithiolan-2-yl, benzisothiazolyl S,S-dioxido, trimethylsilyl(TMS), triethylsilyl (TES), triisopropylsilyl (TIPS),dimethylisopropylsilyl (IPDMS), diethylisopropylsilyl (DEIPS),dimethylthexylsilyl, t-butyldimethylsilyl (TBDMS), t-butyldiphenylsilyl(TBDPS), tribenzylsilyl, tri-p-xylylsilyl, triphenylsilyl,diphenylmethylsilyl (DPMS), t-butylmethoxyphenylsilyl (TBMPS), formate,benzoylformate, acetate, chloroacetate, dichloroacetate,trichloroacetate, trifluoroacetate, methoxyacetate,triphenylmethoxyacetate, phenoxyacetate, p-chlorophenoxyacetate,3-phenylpropionate, 4-oxopentanoate (levulinate),4,4-(ethylenedithio)pentanoate (levulinoyldithioacetal), pivaloate,adamantoate, crotonate, 4-methoxycrotonate, benzoate, p-phenylbenzoate,2,4,6-trimethylbenzoate (mesitoate), alkyl methyl carbonate,9-fluorenylmethyl carbonate (Fmoc), alkyl ethyl carbonate, alkyl2,2,2-trichloroethyl carbonate (Troc), 2-(trimethylsilyl)ethyl carbonate(TMSEC), 2-(phenylsulfonyl) ethyl carbonate (Psec),2-(triphenylphosphonio) ethyl carbonate (Peoc), alkyl isobutylcarbonate, alkyl vinyl carbonate alkyl allyl carbonate, alkylp-nitrophenyl carbonate, alkyl benzyl carbonate, alkyl p-methoxybenzylcarbonate, alkyl 3,4-dimethoxybenzyl carbonate, alkyl o-nitrobenzylcarbonate, alkyl p-nitrobenzyl carbonate, alkyl S-benzyl thiocarbonate,4-ethoxy-1-napththyl carbonate, methyl dithiocarbonate, 2-iodobenzoate,4-azidobutyrate, 4-nitro-4-methylpentanoate, o-(dibromomethyl)benzoate,2-formylbenzenesulfonate, 2-(methylthiomethoxy)ethyl,4-(methylthiomethoxy)butyrate, 2-(methylthiomethoxymethyl)benzoate,2,6-dichloro-4-methylphenoxyacetate,2,6-dichloro-4-(1,1,3,3-tetramethylbutyl)phenoxyacetate,2,4-bis(1,1-dimethylpropyl)phenoxyacetate, chlorodiphenylacetate,isobutyrate, monosuccinoate, (E)-2-methyl-2-butenoate,o-(methoxycarbonyl)benzoate, α-naphthoate, nitrate, alkylN,N,N′,N′-tetramethylphosphorodiamidate, alkyl N-phenylcarbamate,borate, dimethylphosphinothioyl, alkyl 2,4-dinitrophenylsulfenate,sulfate, methanesulfonate (mesylate), benzylsulfonate, and tosylate(Ts). For protecting 1,2- or 1,3-diols, the protecting groups includemethylene acetal, ethylidene acetal, 1-t-butylethylidene ketal,1-phenylethylidene ketal, (4-methoxyphenyl)ethylidene acetal,2,2,2-trichloroethylidene acetal, acetonide, cyclopentylidene ketal,cyclohexylidene ketal, cycloheptylidene ketal, benzylidene acetal,p-methoxybenzylidene acetal, 2,4-dimethoxybenzylidene ketal,3,4-dimethoxybenzylidene acetal, 2-nitrobenzylidene acetal,methoxymethylene acetal, ethoxymethylene acetal, dimethoxymethyleneortho ester, 1-methoxyethylidene ortho ester, 1-ethoxyethylidine orthoester, 1,2-dimethoxyethylidene ortho ester, α-methoxybenzylidene orthoester, 1-(N,N-dimethylamino)ethylidene derivative,α-(N,N′-dimethylamino)benzylidene derivative, 2-oxacyclopentylideneortho ester, di-t-butylsilylene group (DTBS),1,3-(1,1,3,3-tetraisopropyldisiloxanylidene) derivative (TIPDS),tetra-t-butoxydisiloxane-1,3-diylidene derivative (TBDS), cycliccarbonates, cyclic boronates, ethyl boronate, and phenyl boronate.Amino-protecting groups include methyl carbamate, ethyl carbamante,9-fluorenylmethyl carbamate (Fmoc), 9-(2-sulfo)fluorenylmethylcarbamate, 9-(2,7-dibromo)fluoroenylmethyl carbamate,2,7-di-t-butyl-[9-(10,10-dioxo-10,10,10,10-tetrahydrothioxanthyl)]methylcarbamate (DBD-Tmoc), 4-methoxyphenacyl carbamate (Phenoc),2,2,2-trichloroethyl carbamate (Troc), 2-trimethylsilylethyl carbamate(Teoc), 2-phenylethyl carbamate (hZ), 1-(1-adamantyl)-1-methylethylcarbamate (Adpoc), 1,1-dimethyl-2-haloethyl carbamate,1,1-dimethyl-2,2-dibromoethyl carbamate (DB-t-BOC),1,1-dimethyl-2,2,2-trichloroethyl carbamate (TCBOC),1-methyl-1-(4-biphenylyl)ethyl carbamate (Bpoc),1-(3,5-di-t-butylphenyl)-1-methylethyl carbamate (t-Bumeoc), 2-(2′- and4′-pyridyl)ethyl carbamate (Pyoc), 2-(N,N-dicyclohexylcarboxamido)ethylcarbamate, t-butyl carbamate (BOC), 1-adamantyl carbamate (Adoc), vinylcarbamate (Voc), allyl carbamate (Alloc), 1-isopropylallyl carbamate(Ipaoc), cinnamyl carbamate (Coc), 4-nitrocinnamyl carbamate (Noc),8-quinolyl carbamate, N-hydroxypiperidinyl carbamate, alkyldithiocarbamate, benzyl carbamate (Cbz), p-methoxybenzyl carbamate (Moz),p-nitobenzyl carbamate, p-bromobenzyl carbamate, p-chlorobenzylcarbamate, 2,4-dichlorobenzyl carbamate, 4-methylsulfinylbenzylcarbamate (Msz), 9-anthrylmethyl carbamate, diphenylmethyl carbamate,2-methylthioethyl carbamate, 2-methylsulfonylethyl carbamate,2-(p-toluenesulfonyl)ethyl carbamate, [2-(1,3-dithianyl)]methylcarbamate (Dmoc), 4-methylthiophenyl carbamate (Mtpc),2,4-dimethylthiophenyl carbamate (Bmpc), 2-phosphonioethyl carbamate(Peoc), 2-triphenylphosphonioisopropyl carbamate (Ppoc),1,1-dimethyl-2-cyanoethyl carbamate, m-chloro-p-acyloxybenzyl carbamate,p-(dihydroxyboryl)benzyl carbamate, 5-benzisoxazolylmethyl carbamate,2-(trifluoromethyl)-6-chromonylmethyl carbamate (Tcroc), m-nitrophenylcarbamate, 3,5-dimethoxybenzyl carbamate, o-nitrobenzyl carbamate,3,4-dimethoxy-6-nitrobenzyl carbamate, phenyl(o-nitrophenyl)methylcarbamate, phenothiazinyl-(10)-carbonyl derivative,N′-p-toluenesulfonylaminocarbonyl derivative, N′-phenylaminothiocarbonylderivative, t-amyl carbamate, S-benzyl thiocarbamate, p-cyanobenzylcarbamate, cyclobutyl carbamate, cyclohexyl carbamate, cyclopentylcarbamate, cyclopropylmethyl carbamate, p-decyloxybenzyl carbamate,2,2-dimethoxycarbonylvinyl carbamate, o-(N,N-dimethylcarboxamido)benzylcarbamate, 1,1-dimethyl-3-(N,N-dimethylcarboxamido)propyl carbamate,1,1-dimethylpropynyl carbamate, di(2-pyridyl)methyl carbamate,2-furanylmethyl carbamate, 2-iodoethyl carbamate, isoborynl carbamate,isobutyl carbamate, isonicotinyl carbamate,p-(p′-methoxyphenylazo)benzyl carbamate, 1-methylcyclobutyl carbamate,1-methylcyclohexyl carbamate, 1-methyl-1-cyclopropylmethyl carbamate,1-methyl-1-(3,5-dimethoxyphenyl)ethyl carbamate,1-methyl-1-(p-phenylazophenyl)ethyl carbamate, 1-methyl-1-phenylethylcarbamate, 1-methyl-1-(4-pyridyl)ethyl carbamate, phenyl carbamate,p-(phenylazo)benzyl carbamate, 2,4,6-tri-t-butylphenyl carbamate,4-(trimethylammonium)benzyl carbamate, 2,4,6-trimethylbenzyl carbamate,formamide, acetamide, chloroacetamide, trichloroacetamide,trifluoroacetamide, phenylacetamide, 3-phenylpropanamide, picolinamide,3-pyridylcarboxamide, N-benzoylphenylalanyl derivative, benzamide,p-phenylbenzamide, o-nitophenylacetamide, o-nitrophenoxyacetamide,acetoacetamide, (N′-dithiobenzyloxycarbonylamino)acetamide,3-(p-hydroxyphenyl)propanamide, 3-(o-nitrophenyl)propanamide,2-methyl-2-(o-nitrophenoxy)propanamide,2-methyl-2-(o-phenylazophenoxy)propanamide, 4-chlorobutanamide,3-methyl-3-nitrobutanamide, o-nitrocinnamide, N-acetylmethioninederivative, o-nitrobenzamide, o-(benzoyloxymethyl)benzamide,4,5-diphenyl-3-oxazolin-2-one, N-phthalimide, N-dithiasuccinimide (Dts),N-2,3-diphenylmaleimide, N-2,5-dimethylpyrrole,N-1,1,4,4-tetramethyldisilylazacyclopentane adduct (STABASE),5-substituted 1,3-dimethyl-1,3,5-triazacyclohexan-2-one, 5-substituted1,3-dibenzyl-1,3,5-triazacyclohexan-2-one, 1-substituted3,5-dinitro-4-pyridone, N-methylamine, N-allylamine,N-[2-(trimethylsilyl)ethoxy]methylamine (SEM), N-3-acetoxypropylamine,N-(1-isopropyl-4-nitro-2-oxo-3-pyroolin-3-yl)amine, quaternary ammoniumsalts, N-benzylamine, N-di(4-methoxyphenyl)methylamine,N-5-dibenzosuberylamine, N-triphenylmethylamine (Tr),N-[(4-methoxyphenyl)diphenylmethyl]amine (MMTr),N-9-phenylfluorenylamine (PhF),N-2,7-dichloro-9-fluorenylmethyleneamine, N-ferrocenylmethylamino (Fcm),N-2-picolylamino N′-oxide, N-1,1-dimethylthiomethyleneamine,N-benzylideneamine, N-p-methoxybenzylideneamine,N-diphenylmethyleneamine, N-[(2-pyridyl)mesityl]methyleneamine,N—(N′,N′-dimethylaminomethylene)amine, N,N′-isopropylidenediamine,N-p-nitrobenzylideneamine, N-salicylideneamine,N-5-chlorosalicylideneamine,N-(5-chloro-2-hydroxyphenyl)phenylmethyleneamine,N-cyclohexylideneamine, N-(5,5-dimethyl-3-oxo-1-cyclohexenyl)amine,N-borane derivative, N-diphenylborinic acid derivative,N-[phenyl(pentacarbonylchromium- or tungsten)carbonyl]amine, N-copperchelate, N-zinc chelate, N-nitroamine, N-nitrosoamine, amine N-oxide,diphenylphosphinamide (Dpp), dimethylthiophosphinamide (Mpt),diphenylthiophosphinamide (Ppt), dialkyl phosphoramidates, dibenzylphosphoramidate, diphenyl phosphoramidate, benzenesulfenamide,o-nitrobenzenesulfenamide (Nps), 2,4-dinitrobenzenesulfenamide,pentachlorobenzenesulfenamide, 2-nitro-4-methoxybenzenesulfenamide,triphenylmethylsulfenamide, 3-nitropyridinesulfenamide (Npys),p-toluenesulfonamide (Ts), benzenesulfonamide,2,3,6-trimethyl-4-methoxybenzenesulfonamide (Mtr),2,4,6-trimethoxybenzenesulfonamide (Mtb),2,6-dimethyl-4-methoxybenzenesulfonamide (Pme),2,3,5,6-tetramethyl-4-methoxybenzenesulfonamide (Mte),4-methoxybenzenesulfonamide (Mbs), 2,4,6-trimethylbenzenesulfonamide(Mts), 2,6-dimethoxy-4-methylbenzenesulfonamide (iMds),2,2,5,7,8-pentamethylchroman-6-sulfonamide (Pmc), methanesulfonamide(Ms), (3-trimethyl silylethanesulfonamide (SES),9-anthracenesulfonamide,4-(4′,8′-dimethoxynaphthylmethyl)benzenesulfonamide (DNMBS),benzylsulfonamide, trifluoromethylsulfonamide, and phenacylsulfonamide.Exemplary protecting groups are detailed herein, however, it will beappreciated that the present invention is not intended to be limited tothese protecting groups; rather, a variety of additional equivalentprotecting groups can be readily identified using the above criteria andutilized in the method of the present invention. Additionally, a varietyof protecting groups are described by Greene and Wuts (supra).

As described herein, compounds of the invention may contain “optionallysubstituted” moieties. In general, the term “substituted”, whetherpreceded by the term “optionally” or not, means that one or morehydrogens of the designated moiety are replaced with a suitablesubstituent. Unless otherwise indicated, an “optionally substituted”group may have a suitable substituent at each substitutable position ofthe group, and when more than one position in any given structure may besubstituted with more than one substituent selected from a specifiedgroup, the substituent may be either the same or different at everyposition. Combinations of substituents envisioned by this invention arepreferably those that result in the formation of stable or chemicallyfeasible compounds. The term “stable”, as used herein, refers tocompounds that are not substantially altered when subjected toconditions to allow for their production, detection, and, in certainembodiments, their recovery, purification, and use for one or more ofthe purposes disclosed herein.

Suitable monovalent substituents on a substitutable carbon atom of an“optionally substituted” group are independently halogen;—(CH₂)₀₋₄R^(◯); —(CH₂)₀₋₄OR^(◯); —O—(CH₂)₀₋₄C(O)OR^(◯);—(CH₂)₀₋₄CH(OR^(◯))₂; —(CH₂)₀₋₄SR^(◯); —(CH₂)₀₋₄Ph, which may besubstituted with R^(◯); —(CH₂)₀₋₄O(CH₂)₀₋₁Ph which may be substitutedwith R^(◯); —CH═CHPh, which may be substituted with R^(◯); —NO₂; —CN;—N₃; —(CH₂)₀₋₄N(R^(◯))₂; —(CH₂)₀₋₄N(R^(◯))C(O)R^(◯); —N(R^(◯))C(S)R^(◯);—(CH₂)₀₋₄N(R^(◯))C(O)NR^(◯) ₂; —N(R^(◯))C(S)NR^(◯) ₂;—(CH₂)₀₋₄N(R^(◯))C(O)OR^(◯); —N(R^(◯))N(R^(◯))C(O)R^(◯);—N(R^(◯))N(R^(◯))C(O)NR^(◯) ₂; —N(R^(◯))N(R^(◯))C(O)OR^(◯);—(CH₂)₀₋₄C(O)R; —C(S)R^(◯); —(CH₂)₀₋₄C(O)OR^(◯); —(CH₂)₀₋₄C(O)N(R^(◯))₂;—(CH₂)₀₋₄C(O)SR^(◯); —(CH₂)₀₋₄C(O)OSiR^(◯) ₃; —(CH₂)₀₋₄OC(O)R^(◯);—OC(O)(CH₂)₀₋₄SR—, SC(S)SR^(◯); —(CH₂)₀₋₄SC(O)R; —(CH₂)₀₋₄C(O)NR^(◯) ₂;—C(S)NR^(◯) ₂; —C(S)SR^(◯); —SC(S)SRO, —(CH₂)₀₋₄OC(O)NR^(◯) ₂;—C(O)N(OR^(◯))R^(◯); —C(O)C(O)R^(◯); —C(O)CH₂C(O)R^(◯);—C(NOR^(◯))R^(◯); —(CH₂)₀₋₄SSR^(◯); —(CH₂)₀₋₄S(O)₂R^(◯);—(CH₂)₀₋₄S(O)₂OR^(◯); —(CH₂)₀₋₄OS(O)₂R^(◯); —S(O)₂NR^(◯) ₂;—(CH₂)₀₋₄S(O)R^(◯); —N(R^(◯))S(O)₂NR^(◯) ₂; —N(R^(◯))S(O)₂R^(◯);—N(OR^(◯))R^(◯); —C(NH)NR^(◯) ₂; —P(O)₂R^(◯); —P(O)R^(◯) ₂; —OP(O)R^(◯)₂; —OP(O)(OR^(◯))₂; SiR^(◯) ₃; —(C₁₋₄ straight or branchedalkylene)O—N(R^(◯))₂; or —(C₁₋₄ straight or branchedalkylene)C(O)O—N(R^(◯))₂, wherein each R^(◯) may be substituted asdefined below and is independently hydrogen, C₁₋₈ aliphatic, —CH₂Ph,—O(CH₂)₀₋₁Ph, or a 5-6-membered saturated, partially unsaturated, oraryl ring having 0-4 heteroatoms independently selected from nitrogen,oxygen, or sulfur, or, notwithstanding the definition above, twoindependent occurrences of R^(◯), taken together with their interveningatom(s), form a 3-12-membered saturated, partially unsaturated, or arylmono- or polycyclic ring having 0-4 heteroatoms independently selectedfrom nitrogen, oxygen, or sulfur, which may be substituted as definedbelow.

Suitable monovalent substituents on R^(◯) (or the ring formed by takingtwo independent occurrences of R^(◯) together with their interveningatoms), are independently halogen, —(CH₂)₀₋₂R^(), -(haloR^()),—(CH₂)₀₋₂OH, —(CH₂)₀₋₂OR^(), —(CH₂)₀₋₂CH(OR^())₂; —O(haloR^()), —CN,—N₃, —(CH₂)₀₋₂C(O)R^(), —(CH₂)₀₋₂C(O)OH, —(CH₂)₀₋₂C(O)OR^(),—(CH₂)₀₋₄C(O)N(R^(◯))₂; —(CH₂)₀₋₂SR^(), —(CH₂)₀₋₂SH, —(CH₂)₀₋₂NH₂,—(CH₂)₀₋₂NHR^(), —(CH₂)₀₋₂NR^() ₂, —NO₂, —SiR^() ₃, —OSiR^() ₃,—C(O)SR^(), —(C₁₋₄ straight or branched alkylene)C(O)OR^(), or—SSR^() wherein each R^() is unsubstituted or where preceded by “halo”is substituted only with one or more halogens, and is independentlyselected from C₁₋₄ aliphatic, —CH₂Ph, —O(CH₂)₀₋₁Ph, or a 5-6-memberedsaturated, partially unsaturated, or aryl ring having 0-4 heteroatomsindependently selected from nitrogen, oxygen, or sulfur. Suitabledivalent substituents on a saturated carbon atom of R^(◯) include ═O and═S.

Suitable divalent substituents on a saturated carbon atom of an“optionally substituted” group include the following: ═O, ═S, ═NNR*₂,═NNHC(O)R*, ═NNHC(O)OR*, ═NNHS(O)₂R*, ═NR*, ═NOR*, —O(C(R*₂))₂₋₃O—, or—S(C(R*₂))₂₋₃S—, wherein each independent occurrence of R* is selectedfrom hydrogen, C₁₋₆ aliphatic which may be substituted as defined below,or an unsubstituted 5-6-membered saturated, partially unsaturated, oraryl ring having 0-4 heteroatoms independently selected from nitrogen,oxygen, or sulfur. Suitable divalent substituents that are bound tovicinal substitutable carbons of an “optionally substituted” groupinclude: —O(CR*₂)₂₋₃O—, wherein each independent occurrence of R* isselected from hydrogen, C₁₋₆ aliphatic which may be substituted asdefined below, or an unsubstituted 5-6-membered saturated, partiallyunsaturated, or aryl ring having 0-4 heteroatoms independently selectedfrom nitrogen, oxygen, or sulfur.

Suitable substituents on the aliphatic group of R* include halogen,—R^(), -(haloR^()), —OH, —OR^(), —O(haloR^()), —CN, —C(O)OH,—C(O)OR^(), —NH₂, —NHR^(), —NR*₂, or —NO₂, wherein each R^() isunsubstituted or where preceded by “halo” is substituted only with oneor more halogens, and is independently C₁₋₄ aliphatic, —CH₂Ph,—O(CH₂)₀₋₁Ph, or a 5-6-membered saturated, partially unsaturated, oraryl ring having 0-4 heteroatoms independently selected from nitrogen,oxygen, or sulfur.

Suitable substituents on a substitutable nitrogen of an “optionallysubstituted” group include —R^(†), —NR^(†) ₂, —C(O)R^(†), —C(O)OR^(†),—C(O)C(O)R^(†), —C(O)CH₂C(O)R^(†), —S(O)₂R^(†), —S(O)₂NR^(†) ₂,—C(S)NR^(†) ₂, —C(NH)NR^(†) ₂, or —N(R^(†))S(O)₂R^(†); wherein eachR^(†) is independently hydrogen, C₁₋₆ aliphatic which may be substitutedas defined below, unsubstituted —OPh, or an unsubstituted 5-6-memberedsaturated, partially unsaturated, or aryl ring having 0-4 heteroatomsindependently selected from nitrogen, oxygen, or sulfur, or,notwithstanding the definition above, two independent occurrences ofR^(†), taken together with their intervening atom(s) form anunsubstituted 3-12-membered saturated, partially unsaturated, or arylmono- or bicyclic ring having 0-4 heteroatoms independently selectedfrom nitrogen, oxygen, or sulfur.

Suitable substituents on the aliphatic group of R^(†) are independentlyhalogen, —R^(), -(haloR^()), —OH, —OR^(), —O(haloR^()), —CN,—C(O)OH, —C(O)OR^(), —NH₂, —NHR^(), —NR^() ₂, or —NO₂, wherein eachR^() is unsubstituted or where preceded by “halo” is substituted onlywith one or more halogens, and is independently C₁₋₄ aliphatic, —CH₂Ph,—O(CH₂)₀₋₁Ph, or a 5-6-membered saturated, partially unsaturated, oraryl ring having 0-4 heteroatoms independently selected from nitrogen,oxygen, or sulfur.

As used herein, the term “tautomer” includes two or moreinterconvertible compounds resulting from at least one formal migrationof a hydrogen atom and at least one change in valency (e.g., a singlebond to a double bond, a triple bond to a single bond, or vice versa).The exact ratio of the tautomers depends on several factors, includingtemperature, solvent, and pH. Tautomerizations (i.e., the reactionproviding a tautomeric pair) may be catalyzed by acid or base. Exemplarytautomerizations include keto-to-enol; amide-to-imide; lactam-to-lactim;enamine-to-imine; and enamine-to-(a different) enamine tautomerizations.

As used herein, the term “catalyst” refers to a substance the presenceof which increases the rate and/or extent of a chemical reaction, whilenot being consumed or undergoing a permanent chemical change itself.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1A & FIG. 1B depict examples of masked hydroxyl groups undergoingdeprotection to yield polypropylene carbonate having hydroxyl endgroups. Polymer products have either a remnant of a chain transfer agent(FIG. 1A) or are pure polycarbonate (FIG. IB).

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS I. Polymerization Systems ofthe Invention

In one aspect, the present invention provides polymerization systems forthe copolymerization of CO₂ and epoxides to produce polycarbonate polyolresins with a high proportion of —OH end-groups. In certain embodiments,a polymerization system includes 1) a metal complex including apermanent ligand set and at least one ligand that is a polymerizationinitiator, and 2) a chain transfer agent having one or more sitescapable of initiating copolymerization of epoxides and CO₂, wherein thechain transfer agent contains one or more masked hydroxyl groups. Insome embodiments, a polymerization system further includes aco-catalyst. In certain embodiments, a ligand that is a polymerizationinitiator has a plurality of polymer initiation sites.

I.a. Chain Transfer Agents

Chain transfer agents suitable for the present invention include anycompound having one or more sites capable of initiating chain growth inthe co-polymerization of an epoxide and carbon dioxide, wherein thechain transfer agent contains one or more masked hydroxyl groups.Preferably such compounds do not have other functional groups thatinterfere with the polymerization.

As used herein, the term “masked hydroxyl group” refers to a chemicalmoiety which, upon exposure to suitable conditions, is converted to, or“unmasks”, a hydroxyl group. In some embodiments, a masked hydroxylgroup is hydroxyl group bearing a protecting group. In certainembodiments, such masked hydroxyl groups are unmasked under suitabledeprotection conditions to provide a free hydroxyl group.

The present invention encompasses the recognition that a chain transferagent bearing one or more protected hydroxyl groups may, followingpolymerization and incorporation of the chain transfer agent into thepolymer, be deprotected to reveal free hydroxyl groups. In someembodiments, the free hydroxyl groups are located at the polymer chainends. For one such example, the use of ethylene glycol bearing aprotecting group on one hydroxyl group, HO(CH₂)₂OR^(PG), as a chaintransfer agent in a polymerization with propylene oxide and CO₂ providespolypropylene carbonate (PPC) bearing the protected ethylene glycolgroup on one end. Removal of the protecting group provides PPC having afree hydroxyl group on this terminus. (It will be understood that uponcompletion of polymerization the other terminus also bears a freehydroxyl group as well.) See FIG. 1A.

In other embodiments, a masked hydroxyl group is more easily recognizedsubsequent to incorporation of a chain transfer agent into a polymer.Such masked hydroxyl groups may be referred to as “latent” hydroxylgroups. For example, using a reagent “HO—R^(PG)” as a chain transferagent in a polymerization with propylene oxide and CO₂ providespolypropylene carbonate (PPC) bearing an “—OR^(PG)” group on one end.The oxygen atom is now a “latent” hydroxyl group, as deprotection willresult in a free hydroxyl group. (It will be understood that uponcompletion of polymerization the other terminus also bears a freehydroxyl group as well.) See FIG. 1B. Removal of the protecting groupprovides PPC having a free hydroxyl group on this terminus. In addition,the resulting polycarbonate polymer is “pure polycarbonate,” having allhydroxyl end groups and no embedded chain transfer agent or otherfragments derived from monomers other than the epoxide(s) and CO₂. Suchpure polycarbonate is a novel composition.

In some embodiments, a latent hydroxyl group is formed by using a chaintransfer agent selected from the group consisting of benzyl alcohol,methanol, t-butanol, and allyl alcohol. In some embodiments, a latenthydroxyl group is formed by using a chain transfer agent having acarboxylic acid functionality, wherein the resulting ester is hydrolyzedto leave a free hydroxyl group on the polymer terminus.

It will be appreciated that the distinction between protected vs. latenthydroxyl groups is mainly in whether the hydroxyl group being unmaskedhas itself participated in the polymerization reaction. Otherwise, theconcepts are nearly identical, as illustrated in FIG. 1.

In general, for all chain transfer agents described herein for use inthe provided polymerization systems, all chain transfer agents have oneor more masked hydroxyl groups, whether stated explicitly or not.

Suitable chain transfer agents may have a broad array of chemicalstructures. In general, the only requirement is that each molecule ofthe chain transfer agent be capable of initiating one or morepolycarbonate chains, this can occur by several mechanisms including: byring-opening an epoxide monomer, by reacting with carbon dioxidemolecules to yield a moiety capable of sustaining polymer chain growth,or by a combination of these. In some embodiments, a chain transferagent may have two or more functional groups independently capable ofreacting with carbon dioxide or an epoxide; examples of these include,but are not limited to molecules such as diacids, glycols, diols,triols, hydroxyacids, amino acids, amino alcohols, dithiols, mercaptoalcohols, saccharides, catechols, polyethers, etc. In some embodiments,the chain transfer agent may include a multiply active functional groupthat is itself able to react multiple times to initiate more than onepolymer chain. Examples of the latter include, but are not limited tofunctional groups having a single atom capable of reacting multipletimes such as, ammonia, primary amines and water, as well as functionalgroups having more than one nucleophilic atom such as carbonate,amindines, guanidines, phosphates, urea, boronic acids, etc.

In certain embodiments, chain transfer agents of the present disclosurehave a structure Y-A-(Y)_(n′), where:

-   -   each —Y group is independently a functional group capable of        initiating chain growth of epoxide CO₂ copolymers or a protected        hydroxyl group, wherein at least one Y group is a protected        hydroxyl group and the number of Y groups comprising protected        hydroxyl groups is less than the total number of Y groups;    -   -A- is a covalent bond or a multivalent compound; and    -   n′ is an integer between 1 and 10 inclusive.

In some embodiments each Y group is independently selected from thegroup consisting of: —OR^(PG), —OH, —C(O)OH, —C(OR^(y))OH, —OC(R^(y))OH,—NHR^(y), —NHC(O)R^(y), —NHC═NR^(y); —NR^(y)C═NH; —NR^(y)C(NR^(y) ₂)═NH;—NHC(NR₂)═NR^(y); —NHC(O)OR^(y), —NHC(O)NR^(y) ₂; —C(O)NHR^(y),—C(S)NHR^(y), —OC(O)NHR^(y), —OC(S)NHR^(y), —SH, —C(O)SH, —B(OR^(y))OH,—P(O)_(a)(R^(y))_(b)(OR^(y))_(c)(O)_(d)H,—OP(O)_(a)(R^(y))_(b)(OR^(y))_(c)(OH)_(d), —N(R^(y))OH, —ON(R^(y))H;═NOH, ═NN(R^(y))H, where

-   -   each occurrence of R^(y) is independently —H, or an optionally        substituted radical selected from the group consisting of C₁₋₂₀        aliphatic, C₁₋₂₀ heteroaliphatic, 3- to 12-membered        heterocyclic, and 6- to 12-membered aryl,    -   each occurrence of R^(PG) is independently a hydroxyl protecting        group, wherein a single R^(PG) moiety may protect multiple        hydroxyl groups;    -   a and b are each independently 0 or 1,    -   c is 0, 1 or 2,    -   d is 0 or 1, and    -   the sum of a, b, and c is 1 or 2.

In certain embodiments, -A- is a covalent bond. For example, whenY-A-(Y)_(n′) is oxalic acid, -A- is a covalent bond.

In some embodiments, -A- is an optionally substituted radical selectedfrom the group consisting of: straight or branched C₂₋₃₀ aliphatic,straight or branched C₂₋₃₀ heteroaliphatic, 6- to 12-membered aryl, 3-to 12-membered heterocyclic, 5- to 12-membered heteroaryl, polyolefins,polyesters, polyethers, polycarbonates, polyoxymethylene and mixtures oftwo or more of these.

A hydroxyl protecting group is any suitable protecting group as definedabove and as described in classes and subclasses herein. In someembodiments, a hydroxyl protecting group is an ether. In someembodiments, a hydroxyl protecting group is an ester. In someembodiments, a protected hydroxyl group is attached to an aliphaticcarbon. In some embodiments, a protected hydroxyl group is attached toan aryl carbon. In some embodiments, a protecting group protects morethan one hydroxyl group of a chain transfer agent, for example, 1,2- or1,3-diols.

In some embodiments, each —OR^(PG) is selected from the group consistingof an aliphatic ether, a substituted methyl ether, a cycloaliphaticether, an arylalkyl ether, a silyl ether, a formate ester, an aliphaticester, an aryl ester, a carbonate, a carbamate, an acetal, a ketal, acyclic carbonate, and a cyclic boronate.

In certain embodiments, each —OR^(PG) is selected from the groupconsisting of methyl ether, methoxymethyl ether (MOM), methylthiomethylether (MTM), 2-methoxyethoxymethyl ether (MEM),bis(2-chloroethyoxy)methyl ether, tetrahydropyranyl ether (THP),tetrahydrothiopyranyl ether, 4-methoxytetrahydropyranyl ether,4-methoxytetrahydrothiopyranyl ether, tetrahydrofuranyl ether,tetrahydrothiofuranyl ether, 1-ethoxyethyl ether,1-methyl-1-methoxyether ether, 2-(phenylselenyl)ethyl ether, t-butylether, allyl ether, benzyl ether, o-nitrobenzyl ether, triphenylmethylether, alpha-naphthyldiphenylmethyl ether, p-methoxyphenyldiphenylmethylether, 9-(9-phenyl-10-oxo)anthryl ether (tritylone), trimethylsilylether (TMS), isopropyldimethylsilyl ether, t-butyldimethylsilyl ether(TBDMS), t-butyldiphenylsilyl ether, tribenzylsilyl ether, andtriisopropylsilyl ether.

In some embodiments, each —OR^(PG) is selected from the group consistingof formate ester, acetate ester, trichloroacetate ester, phenoxyacetateester, isobutyrate ester, pivaloate ester, adamantoate ester, benzoateester, 2,4,6-trimethylbenzoate (mesitoate) ester, methyl carbonate,2,2,2-trichloroethyl carbonate, allyl carbonate, p-nitrophenylcarbonate, benzyl carbonate, p-nitrobenzyl carbonate, benzyl carbonate,N-phenylcarbamate, nitrate ester, and 2,4-dinitrophenylsulfenate ester.

In some embodiments, each —OR^(PG) is selected from the group consistingof a methylenedioxy derivative, ethylidene acetal, an acetonide,benzylidene acetal, p-methoxybenzylidene acetal, methoxymethyleneacetal, a dimethoxymethylenedioxy derivative, a cyclic carbonate, and acyclic boronate.

In some embodiments, an acidic hydrogen atom bound in any of the abovefunctional groups may be replaced by a metal atom or an organic cationwithout departing from the present invention (e.g. —C(O)OH may insteadbe —C(O)O⁻Na⁺, —C(O)O⁻N⁺(R)₄, —C(O)O⁻(Ca²⁺)_(0.5), —C(O)O⁻PPN⁺ or —SH,may be —S⁻Na⁺ etc.) such alternatives are specifically included hereinand alternate embodiments employing such salts are implicitlyencompassed by the disclosure and examples herein.

In certain embodiments, each Y group is independently selected from thegroup consisting of —OR^(PG), —OH, and —C(O)OH. In some embodiments, oneor more Y groups are hydroxyl or a hydroxy salt. In certain embodiments,each hydroxyl group is a primary or secondary alcohol. In otherembodiments, a hydroxyl group is bonded to an aromatic or heteroaromaticring. In certain embodiments, a hydroxyl group is a phenol. In someembodiments, a hydroxyl group is benzylic, allylic or propargylic. Inother embodiments, hydroxyl groups are part of a carbohydrate. In otherembodiments, a hydroxyl group is part of a polymer or oligomer such as apolyether, a polyester, a polyvinyl alcohol or a hydroxy-functionalizedor hydroxy-terminated polyolefin.

In some embodiments, a chain transfer agent is a polyhydric alcohol,wherein one or more hydroxyl groups are protected. In certainembodiments, the polyhydric alcohol is a diol, while in otherembodiments the polyhydric alcohol is a triol, a tetraol or a higherpolyol. In certain embodiments, n′ is 1, (i.e. two Y groups are present)and one Y group is a protected hydroxyl group. In some embodiments, twohydroxyl groups are on adjacent carbons (i.e. the chain transfer agentis a glycol), wherein one or both hydroxyls are protected.

In some embodiments, a chain transfer agent is selected from the groupconsisting of 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol,1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol,2,2-dimethylpropane-1,3-diol, 2-butyl-2-ethylpropane-1,3-diol,1,5-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol,1,12-dodecanediol, 2,2,4,4-tetramethylcyclobutane-1,3-diol,1,3-cyclopentanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol,1,4-cyclohexanediol, 1,2-cyclohexanedimethanol,1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, and1,4-cyclohexanediethanol.

In certain embodiments, a chain transfer agent is selected fromdiethylene glycol, triethylene glycol, tetraethylene glycol, higherpoly(ethylene glycol), preferrably those having number average molecularweights of from 220 to about 2000 g/mol, dipropylene glycol,tripropylene glycol, and higher poly(propylene glycols) preferrablythose having number average molecular weights of from 234 to about 2000g/mol.

In some embodiments, two hydroxyl groups are on non-adjacent carbons,wherein one or both hydroxyls are protected. In certain embodiments, twohydroxyl groups are on the opposite ends of a chain (i.e. the chaintransfer agent is an α-ω diol), wherein one or both hydroxyls areprotected. In certain embodiments, such α-ω diols include C₃ to C₂₀aliphatic chains (i.e. -A- is an optionally substituted C₃₋₂₀ aliphaticchain). In certain embodiments, such α-ω diols comprise a polyether(i.e. -A- is a polyether chain). In certain embodiments, such α-ω diolscomprise a hydroxy-terminated polyolefin (i.e. -A- is a polyolefinchain). In certain embodiments, such α-ω diols comprise paraformaldehyde(i.e. -A- is a polyoxymethylene chain).

In certain embodiments, diol chain transfer agents includehydroxyl-terminated polyolefins. Such materials include polymers sold bySartomer Inc. under the trade name Krasol®. In other embodiments, diolchain transfer agents can include hydroxyl-terminated polyisobutylenes(PIB-diols and -triols) such as Polytail® H or Polytail®HA fromMitsubish Chemical Co. Other examples include hydroxyl-terminatedpolybutadienelstyrene (HTBS).

Yet other examples of suitable diols include 4,4′-(1-methylethylidene)bis[cyclohexanol], 2,2′-methylenebis[phenol], 4,4′-methylenebis[phenol],4,4′-(phenylmethylene)bis[phenol], 4,4′-(diphenylmethylene)bis[phenol],4,4′-(1,2-ethanediyl)bis[phenol], 4,4′-(1,2-cyclohexanediyl)bis[phenol],4,4′-(1,3-cyclohexanediyl)bis[phenol],4,4′-(1,4-cyclohexanediyl)bis[phenol], 4,4′-ethylidenebis[phenol],4,4′-(1-phenylethylidene)bis[phenol], 4,4′-propylidenebis[phenol],4,4′-cyclohexylidenebis[phenol], 4,4′-(1-methylethylidene)bis[phenol],4,4′-(1-methylpropylidene)bis[phenol],4,4′-(1-ethylpropylidene)bis[phenol], 4,4′-cyclohexylidenebis[phenol],4,4′-(2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diyldi-2,1-ethanediyl)bis[phenol], 1,2-benzenedimethanol, 1,3-benzenedimethanol,1,4-benzenedimethanol,4,4′-[1,3-phenylenebis(1-methylethylidene)]bis[phenol],4,4′-[1,4-phenylenebis(1-methylethylidene)]bis[phenol], phenolphthalein,4,4′-(1-methylidene)bis[2-methylphenol],4,4′-(1-methylethylidene)bis[2-(1-methylethyl)phenol],2,2′-methylenebis[4-methyl-6-(1-methylethyl)phenol].

In certain embodiments, a chain transfer agent is selected frommonoprotected 1,3 propane diol, 1,4 butane diol, dipropylene glycol,diethylene glycol, and isosorbide

In certain embodiments, a chain transfer agent is a polyhydric phenolderivative.

In some embodiments, a polyhydric alcohol provided as a chain transferagent is a triol, a tetraol or a higher polyol. Suitable triols mayinclude, but are not limited to: aliphatic triols having a molecularweight less than 500 such as trimethylolethane; trimethylolpropane;glycerol; 1,2,4-butanetriol; 1,2,6-hexanetriol;tris(2-hydroxyethyl)isocyanurate;hexahydro-1,3,5-tris(hydroxyethyl)-s-triazine;6-methylheptane-1,3,5-triol; polypropylene oxide triol; and polyestertriols.

In certain other embodiments, a polyol is a tetraol. Examples ofsuitable tetraols include, but are not limited to: erythritol,pentaerythritol; 2,2′-dihydroxymethyl-1,3-propanediol; and2,2′-(oxydimethylene) bis-(2-ethyl-1,3-propanediol).

In still other embodiments, a polyol is a carbohydrate. Examples ofsuitable carbohydrates include sugar alcohols, monosaccharides,disaccharides, oligosaccharides and polysaccharides and higher oligomerssuch as starch and starch derivatives.

In some embodiments, one —OH group of a diol is phenolic and the otheris aliphatic, wherein one of the —OH groups is protected. In otherembodiments, each hydroxy group is phenolic. In certain embodiments, achain transfer agent is an optionally substituted catechol, resorcinolor hydroquinone derivative.

In some embodiments where a Y-group is —OH, the —OH group is an enoltautomer of a carbonyl group. In some embodiments where a Y group is—OH, the —OH group is a carbonyl hydrate or a hemiacetal.

In some embodiments, n′ is 1 to 4. In some embodiments, n′ is 1. In someembodiments, n′ is 2. In some embodiments, n′ is 3. In some embodiments,n′ is 4. In some embodiments, n′ is 5.

In other embodiments where n′ is 1, only one Y group is —OR^(PG), andthe other Y group is selected from the group consisting of: —OH,—C(O)OH, —C(OR^(y))OH, —OC(R^(y))OH, —NHR^(y), —NHC(O)R^(y),—NHC(O)OR^(y), —C(O)NHR^(y), —C(S)NHR^(y), —OC(O)NHR^(y), —OC(S)NHR^(y),—SH, —C(O)SH, —B(OR^(y))OH, —P(O)_(a)(R^(y))_(b)(OR^(y))_(c)OH,—OP(O)_(a)(R^(y))_(b)(OR^(y))_(c)OH, —N(R^(y))OH, —ON(R^(y))H; ═NOH,═NN(R^(y))H. In particular embodiments, n′ is 1, one Y group is—OR^(PG), and the other Y group is selected from the group consisting of—OH, —SH, —C(O)OH, —NHR^(y), and —C(O)NHR^(y). In certain embodiments,n′ is 1, one Y group is —OR^(PG), and the other Y group is —OH. Incertain embodiments, n′ is 1, one Y group is —OR^(PG), and the other Ygroup is —C(O)OH. In other embodiments where n′ is 1, one Y group is—OR^(PG) and the other Y group is —SH. In other embodiments where n′ is1, one Y group is —OR^(PG) and one Y group is —NHR^(y). In certainembodiments, n′ is 2, and one or two Y groups is —OR^(PG) (i.e. thechain transfer agent is a triol). In some embodiments where n′ is 2, twoY groups are —OR^(PG), and the third Y group is selected from the groupconsisting of —OH, —SH, —C(O)OH, —NHR^(y), and —C(O)NHR^(y). In otherembodiments where n′ is 2, only one Y group is —OR^(PG), while the othertwo Y groups are independently selected from the group consisting of—OH, —SH, —C(O)OH, —NHR^(y), and —C(O)NHR^(y).

In some embodiments, polyalcohol chain transfer agents encompassnaturally occurring materials such as sugar alcohols, carbohydrates,saccharides, polysaccharides, starch, starch derivatives, lignins,lignans, partially hydrolyzed triglycerides, and the like, as well asknown derivatives of any of these materials. In certain embodiments, achain transfer agent comprises starch. In certain embodiments, a chaintransfer agent comprises isosorbide.

In other embodiments, at least one Y group of a chain transfer agent isan amine. In some embodiments, at least one Y group is a primary amine.In other embodiments, at least one Y group is a secondary amine. Incertain embodiments, at least one Y group is an aniline or anilinederivative. In some embodiments, at least one Y group is an N—H groupthat is part of a heterocycle.

In certain embodiments, a chain transfer agent comprises a polyamine. Insome embodiments, a chain transfer agent comprises a diamine. In otherembodiments, a chain transfer agent comprises a triamine, tetraamine ora higher amine oligomer.

In certain embodiments, at least one Y group is an amine and one or moreadditional Y groups are independently selected from the group consistingof —OR^(PG), —OH, —C(O)OH, —C(OR^(y))OH, —OC(R^(y))OH, —NHC(O)R^(y),—NHC(O)OR^(y), —C(O)NHR^(y), —C(S)NHR^(y), —OC(O)NHR^(y), —OC(S)NHR^(y),—SH, —C(O)SH, —B(OR^(y))OH, —P(O)_(a)(R^(y))_(b)(OR^(y))_(c)OH,—OP(O)_(a)(R^(y))_(b)(OR^(y))_(c)OH, —N(R^(y))OH, —ON(R^(y))H; ═NOH,═NN(R^(y))H. In certain embodiments, at least one Y group is an amineand one or more additional Y groups are independently selected from thegroup consisting of, —OR^(PG), —OH, —SH, —C(O)OH, and —C(O)NHR^(y).

In some embodiments, at least one Y group is a carboxylic acid or a saltthereof. In some embodiments, all Y groups present are carboxylic acidsalts thereof, while in other embodiments, one or more carboxylic acid Ygroups are present along with one or more other functional groups thatcan initiate the copolymerization. In certain embodiments, at least oneY group is a benzoic acid derivative.

In certain embodiments, a chain transfer agent is a diacid, a triacid ora higher polyacid. In some embodiments, a chain transfer agent is adiacid. In certain embodiments, n′ is 1, and both Y groups present arecarboxylic acids. In certain embodiments, a diacid is phthalic acid,isophthalic acid, terephthalic acid. In certain embodiments, a diacid ismaleic acid, succinic acid, malonic acid, glutaric acid, adipic acid,pimelic acid, suberic acid, or azelaic acid. In some embodiments, achain transfer agent is a triacid. In certain embodiments, a triacid iscitric acid, isocitric acid, cis- or trans-aconitic acid,propane-1,2,3-tricarboxylic acid or trimesic acid.

In certain embodiments, at least one Y group is a carboxylic acid orcarboxylate and one or more additional Y groups are independentlyselected from the group consisting of —OH, —OR^(PG), —C(OR^(y))OH,—OC(R^(y))OH, —NHR^(y), —NHC(O)R^(y), —NHC(O)OR^(y), —C(O)NHR^(y),—C(S)NHR^(y), —OC(O)NHR^(y), —OC(S)NHR^(y), —SH, —C(O)SH, —B(OR^(y))OH,—P(O)_(a)(R^(y))_(b)(OR^(y))_(c)OH, —OP(O)_(a)(R^(y))_(b)(OR^(y))_(c)OH,—N(R^(y))OH, —ON(R^(y))H; ═NOH, ═NN(R^(y))H. In certain embodiments, atleast one Y group is a carboxylic acid and one or more additional Ygroups are independently selected from the group consisting of —OR^(PG),—OH, —SH, —NHR^(y), and —C(O)NHR^(y).

In some embodiments, a chain transfer agent is an amino acid containinga masked hydroxyl group. In certain embodiments, such amino acid chaintransfer agents include the naturally occurring amino acids. In certainembodiments, amino acid chain transfer acids include peptides. In someembodiments, the peptides contain between 2 and about 20 amino acidresidues. In other embodiments, the chain transfer agent is a thiolacid.

In some embodiments, the chain transfer agent is a hydroxy acid, whereinat least one hydroxyl group of the hydroxyl acid is protected. In someembodiments, hydroxy acids are alpha-hydroxy acids. In certainembodiments an alpha hydroxy acid is selected from the group consistingof: glycolic acid, DL-lactic acid, D-lactic acid, L-lactic, citric acidand mandelic acid. In some embodiments, a hydroxy acid is a beta-hydroxyacid. In certain embodiments, a beta hydroxy acid is selected from thegroup consisting of: 3-hydroxypropionic acid, DL 3-hydroxybutryic acid,D-3 hydroxybutryic acid, L 3-hydroxybutyric acid, DL-3-hydroxy valericacid, D-3-hydroxy valeric acid, L-3-hydroxy valeric acid, salicylicacid, and derivatives of salicylic acid. In some embodiments, a hydroxyacid is an α-ω hydroxy acid. In certain embodiments, α-ω hydroxy acidsare selected from the group consisting of optionally substituted C₃₋₂₀aliphatic α-ω hydroxy acids. In certain embodiments, an α-ω hydroxy acidis a polyester oligomeric ester.

In some embodiments, a chain transfer agent comprises one or morecarboxylic acid groups that initiate chain growth in theco-polymerization of an epoxide and carbon dioxide, and the resultingester groups can be hydrolyzed following polymerization to providepolymer chain ends with free hydroxyl groups. In some embodiments, apolycarboxylic acid is used as a chain transfer agent, and followinghydrolysis, the molecular weight of the resulting polymer chains iscorrespondingly lower, as dependent upon the ratio of polymer chainsafter and before hydrolysis.

In some embodiments, a chain transfer agent is a polycarboxylic acid. Incertain embodiments, a chain transfer agent includes a diacid. Incertain embodiments, a chain transfer agent includes a compound selectedfrom the group consisting of:

In certain embodiments, diacid chain transfer agents include carboxyterminated polyolefin polymers. In certain embodiments, carboxyterminated polyolefins include materials such as NISSO-PB C-seriesresins produced by Nippon Soda Co. Ltd.

In some embodiments, the chain transfer agent is selected from the groupconsisting of: phthalic acid, isophthalic acid, terephthalic acid,maleic acid, succinic acid, malonic acid, glutaric acid, adipic acid,pimelic acid, suberic acid, and azelaic acid.

In certain embodiments, a chain transfer agent is a hydroxy acid. Incertain embodiments, a hydroxy acid is selected from the groupconsisting of:

wherein each R^(PG) is independently a hydroxyl protecting group.

In certain embodiments where the provided chain transfer agent includesan acidic functional group, the compound is provided as a salt. Incertain embodiments a carboxylic chain transfer agent is provided as anammonium salt.

In some embodiments, where one or more Y groups is a carboxyl group, achain transfer agent is provided as a carboxylate salt. In certainembodiments, a carboxylate salt is a group I or II metal salt. In someembodiments, a carboxylate salt is an ammonium salt. In certainembodiments, an ammonium cation is NH₄ ⁺. In some embodiments, anammonium cation is a protonated primary, secondary, or tertiary amine.In some embodiments, a salt is a quaternary ammonium salt. In someembodiments, a quaternary ammonium cation of a salt is tetramethyl,tetrabutyl, or trihexylammonium ammonium. In certain embodiments, acarboxylate salt is a phosphonium carboxylate.

In other embodiments, at least one Y group of a chain transfer agent isa thiol. In some embodiments, at least one Y group is a primary thiol.In other embodiments, at least one Y group is a secondary or tertiarythiol. In certain embodiments, at least one Y group is a thiophenol orthiophenol derivative.

In certain embodiments, a chain transfer agent is a polythiol having atleast one masked hydroxyl group. In some embodiments, a chain transferagent is a dithiol. In some embodiments, a chain transfer agent is atrithiol or higher thiol oligomer.

In certain embodiments, at least one Y group is a thiol and one or moreadditional Y groups are independently selected from the group consistingof —OR^(PG), —OH, —C(O)OH, —C(OR^(y))OH, —OC(R^(y))OH, —NHR^(y),—NHC(O)R^(y), —NHC(O)OR^(y), —C(O)NHR^(y), —C(S)NHR^(y), —OC(O)NHR^(y),—OC(S)NHR^(y), —C(O)SH, —B(OR^(y))OH,—P(O)_(a)(R^(y))_(b)(OR^(y))_(c)OH, —OP(O)_(a)(R^(y))_(b)(OR^(y))_(c)OH,—N(R^(y))OH, —ON(R^(y))H; ═NOH, ═NN(R^(y))H. In certain embodiments, atleast one Y group is a thiol and one or more additional Y groups areindependently selected from the group consisting of —OR^(PG), —OH,—NHR^(y), —C(O)OH, and —C(O)NHR^(y). In some embodiments, a chaintransfer agent is a thio alcohol having a protected hydroxyl group.

In certain embodiments, a Y group of a chain transfer agent is an activeNH-containing functional group. In certain embodiments, a nitrogen atomof the NH-containing functional group is nucleophilic. In certainembodiments, a active NH-containing functional group is selected fromthe group consisting of C-linked amides, N-linked amides, O-linkedcarbamates N-linked carbamates, ureas, guanidines, amidines, hydrazones,and N- or C-linked thioamides. In certain embodiments, one or more Ygroups is a primary amide.

In certain embodiments, polymerization systems of the present inventioninclude only one chain transfer agent, while in other embodiments,mixtures of two or more chain transfer agents are used.

In certain embodiments, polymerization systems of the present inventioninclude a solvent in which a chain transfer agent dissolves. In certainembodiments, a chain transfer agent is poorly soluble in the epoxide,but is soluble in a mixture of epoxide and another solvent added to thereaction mixture. In certain embodiments, the solvent added to thepolymerizations system is chosen from the group consisting of esters,nitriles, ketones, aromatic hydrocarbons, ethers, amines andcombinations of two or more of these.

In some embodiments, a chain transfer agent may contain a singlemultiply active functional group. In some embodiments, the chaintransfer agent may contain a single multiply active functional group inaddition to one or more of the Y-groups described above. In certainembodiments, a chain transfer agent may contain two or more multiplyactive functional groups. In certain embodiments, a chain transfer agentmay contain two or more multiply active functional groups in combinationwith one or more of the Y groups described hereinabove.

I.b Metal Centered Catalysts

In some embodiments, polymerization systems of the present inventionincorporate any transition metal complex capable of catalyzing thecopolymerization of carbon dioxide and epoxides. In certain embodiments,the polymerization systems include any of the catalysts disclosed inU.S. Pat. Nos. 7,304,172, and 6,870,004; in PCT Publication NumbersWO2008136591A1, WO2008150033A1, WO2009137540, WO2010028362,WO2010022388, and WO2012037282, and in Chinese Patent ApplicationNumbers CN200710010706, and CN200810229276, the entirety of each ofwhich is hereby incorporated herein by reference.

In certain embodiments, polymerization systems of the present inventioninclude metal complexes denoted L_(p)-M-(L_(I))_(n), where L_(p) is apermanent ligand set, M is a metal atom, and L_(I) is a ligand that is apolymerization initiator, and n is an integer between 0 and 2 inclusiverepresenting the number of initiating ligands present.

I.b.1 Metal Atoms

As described above, metal complexes catalyzing the copolymerization ofcarbon dioxide and epoxides may be used in accordance with the presentinvention. In some embodiments, a metal atom, M, is selected fromperiodic table groups 3-13, inclusive. In certain embodiments, M is atransition metal selected from periodic table groups 5-12, inclusive. Insome embodiments, M is a transition metal selected from periodic tablegroups 4-11, inclusive. In certain embodiments, M is a transition metalselected from periodic table groups 5-10, inclusive. In certainembodiments, M is a transition metal selected from periodic table groups7-9, inclusive. In some embodiments, M is selected from the groupconsisting of Cr, Mn, V, Fe, Co, Mo, W, Ru, Al, and Ni. In someembodiments, M is a metal atom selected from the group consisting of:cobalt; chromium; aluminum; titanium; ruthenium, and manganese. In someembodiments, M is cobalt. In some embodiments, M is chromium. In someembodiments, M is aluminum.

In certain embodiments, a metal complex is a zinc, cobalt, chromium,aluminum, titanium, ruthenium, or manganese complex. In certainembodiments, a metal complex is an aluminum complex. In otherembodiments, a metal complex is a chromium complex. In yet otherembodiments, a metal complex is a zinc complex. In certain otherembodiments, a metal complex is a titanium complex. In still otherembodiments, a metal complex is a ruthenium complex. In certainembodiments, a metal complex is a manganese complex. In certainembodiments, a metal complex is cobalt complex. In certain embodimentswhere a metal complex is a cobalt complex, the cobalt metal has anoxidation state of +3 (i.e., Co(III)). In other embodiments, the cobaltmetal has an oxidation state of +2 (i.e., Co(II)).

I.b.2 Permanent Ligand Sets

A permanent ligand set ‘L_(p)’ comprises one or more ligands that remaincoordinated with a metal center throughout the catalytic cycle. This isin contrast to other ligands such as polymerization initiators, monomermolecules, polymer chains, and solvent molecules that may participate inthe catalytic cycle or may be exchanged under the polymerizationconditions.

In certain embodiments, a permanent ligand set comprises a singlemultidentate ligand that remains associated with the metal center duringcatalysis. In some embodiments, the permanent ligand set includes two ormore ligands that remain associated with the metal center duringcatalysis. In some embodiments, a metal complex comprises a metal atomcoordinated to a single tetradentate ligand while in other embodiments,a metal complex comprises a chelate containing a plurality of individualpermanent ligands. In certain embodiments, a metal complex contains twobidentate ligands. In some embodiments, a metal complex contains atridentate ligand.

In various embodiments, tetradentate ligands suitable for metalcomplexes of the present invention may include, but are not limited to:salen derivatives 1, derivatives of salan ligands 2,bis-2-hydroxybenzamido derivatives 3, derivatives of the Trost ligand 4,porphyrin derivatives 5, derivatives of tetrabenzoporphyrin ligands 6,derivatives of corrole ligands 7, phthalocyaninate derivatives 8, anddibenzotetramethyltetraaza[14]annulene (tmtaa) derivatives 9 or 9′.

-   -   wherein,    -   Q, at each occurrence is independently O or S;    -   R¹ and R^(1′) are independently selected from the group        consisting of: —H, optionally substituted C₁ to C₁₂ aliphatic;        optionally substituted 3- to 14-membered carbocycle; optionally        substituted 3- to 14-membered heterocycle; and R²¹;    -   R² and R^(2′) are independently selected from the group        consisting of: —H; optionally substituted C₁ to C₁₂ aliphatic;        optionally substituted 3- to 14-membered carbocycle; optionally        substituted 3- to 14-membered heterocycle; R¹⁴; R²⁰; and R²¹;    -   R³ and R^(3′) are independently selected from the group        consisting of:        -   —H; optionally substituted C₁ to C₁₂ aliphatic; optionally            substituted 3- to 14-membered carbocycle; optionally            substituted 3- to 14-membered heterocycle, and R²¹;    -   R^(c) at each occurrence is independently selected from the        group consisting of: —H; optionally substituted C₁ to C₁₂        aliphatic; an optionally substituted 3- to 14-membered        carbocycle; an optionally substituted 3- to 14 membered        heterocycle; R²⁰; and R²¹, where two or more R^(c) groups may be        taken together with intervening atoms to form one or more        optionally substituted rings and, when two R^(c) groups are        attached to the same carbon atom, they may be taken together        along with the carbon atom to which they are attached to form a        moiety selected from the group consisting of: an optionally        substituted 3- to 8-membered spirocyclic ring, a carbonyl, an        oxime, a hydrazone, and an imine;    -   R^(d) at each occurrence is independently selected from the        group consisting of: optionally substituted C₁ to C₁₂ aliphatic;        optionally substituted 3- to 14-membered carbocycle; optionally        substituted 3- to 14-membered heterocycle; R²⁰; and R²¹, where        two or more R^(d) groups may be taken together with intervening        atoms to form one or more optionally substituted rings; and    -   represents an optionally substituted moiety covalently linking        two nitrogen atoms,    -   where any of [R^(2′) and R^(3′)], [R² and R³], [R¹ and R²], and        [R^(1′) and R^(2′)] may optionally be taken together with        intervening atoms to form one or more rings which may in turn be        substituted with one or more groups selected from R¹⁴; R²⁰; and        R²¹; and where    -   R¹⁴ at each occurrence is independently selected from the group        consisting of: a        (Z)_(p) group; halogen; optionally substituted C₁ to C₁₂        aliphatic; optionally        substituted 3- to 14-membered carbocycle; optionally substituted        3- to 14-membered heterocycle; —OR¹⁰; —OC(O)R¹³; —OC(O)OR¹³;        —OC(O)NR¹¹R¹²; —CN; —CNO; —C(R¹³)_(z)H_((3-z)); —C(O)R¹³;        —C(O)OR¹³; —C(O)NR¹¹R¹²; —NR¹¹R¹²; —NR¹¹C(O)R¹³; —NR¹¹C(O)OR¹³;        —NR¹¹SO₂R¹³; —N⁺R¹¹R¹²R¹³ X⁻; —P⁺(R¹¹)₃ X⁻; —P(R¹¹)₃═N+═P(R¹¹)₃        X⁻; —As⁺R¹¹R¹²R¹³ X⁻; —NCO; —N₃; —NO₂; —S(O)_(x)R¹³; and        —SO₂NR¹¹R¹²,    -   R²⁰ at each occurrence is independently selected from the group        consisting of: a        (Z)_(p) group; halogen; —OR¹⁰; —OC(O)R¹³; —OC(O)OR¹³; —N⁺(R¹¹)₃        X⁻; —P⁺(R¹¹)₃ X⁻; —P(R¹¹)₃═N⁺═P(R¹¹)₃ X⁻; —As⁺RR¹²R¹³ X⁻;        —OC(O)NR¹¹R¹²; —CN; —CNO; —C(O)R¹³; —C(O)OR¹³; —C(O)NR¹¹R¹²;        —C(R¹³)_(z)H_((3-z)); —NR¹¹R¹²; —NR¹¹C(O)R¹³; —NR¹¹C(O)OR¹³;        —NCO; —NR¹¹SO₂R¹³; —S(O)_(x)R¹³; —S(O)₂NR¹¹R¹²; —NO₂; —N₃; and        —Si(R¹³)_((3-z))[(CH₂)_(k)R¹⁴]_(z),    -   R²¹ at each occurrence is independently selected from the group        consisting of: a        (Z)_(p) group; —(CH₂)_(k)R²⁰; —(CH₂)_(k)—Z″—(CH₂)_(k)R²⁰;        —C(R¹⁷)_(z)H_((3-z)); —(CH₂)_(k)C(R¹⁷)_(z)H_((3-z));        —(CH₂)_(m)—Z″—(CH₂)_(m)C(R¹⁷)_(z)H_((3-z)); —(CH₂)_(k)—Z″—R¹⁶;    -   X⁻ is any anion,    -   Z″ is a divalent linker selected from the group consisting of        —(CH═CH)_(a)—; —(CH≡CH)_(a)—; —C(O)—; —C(═NOR¹¹)—;        —C(═NNR¹¹R¹²)—; —O—; —OC(O)—; —C(O)O—; —OC(O)O—; —N(R¹¹)—;        —N(C(O)R¹³)—; —C(O)NR¹³—; —N(C(O)R¹³)O—; —NR¹³C(O)R¹³N—;        —S(O)_(x)—; a polyether; and a polyamine,    -   R¹⁰ at each occurrence is independently selected from the group        consisting of: —H; optionally substituted C₁₋₁₂ aliphatic; an        optionally substituted 3- to 14-membered carbocycle; an        optionally substituted 3- to 14-membered heterocycle —S(O)₂R¹³;        —Si(R¹⁵)₃; —C(O)R¹³; and a hydroxyl protecting group,    -   R¹¹ and R¹² at each occurrence are independently selected from        the group consisting of: —H; optionally substituted C₁ to C₁₂        aliphatic; an optionally substituted 3- to 14-membered        carbocycle; an optionally substituted 3- to 14-membered        heterocycle; where two or more R¹¹ or R¹² groups can optionally        be taken together with intervening atoms to form an optionally        substituted 3- to 10-membered ring,    -   R¹³ at each occurrence is independently selected from the group        consisting of:        -   —H; optionally substituted C₁ to C₁₂ aliphatic; an            optionally substituted 3- to 14-membered carbocycle; and            optionally substituted 3- to 14-membered heterocycle, where            two or more R¹³ groups on the same molecule may optionally            be taken together to form ring.    -   R¹⁵ at each occurrence is independently selected from the group        consisting of: optionally substituted C₁₋₁₂ aliphatic, an        optionally substituted 3- to 14-membered carbocycle; and an        optionally substituted 3- to 14-membered heterocycle,    -   R¹⁶ at each occurrence is independently selected from the group        consisting of:        -   optionally substituted C₁-C₁₂ aliphatic, an optionally            substituted 3- to 14-membered carbocycle; an optionally            substituted 3- to 14-membered heterocycle; and            —C(R¹⁷)_(z)H_((3-z)),    -   R¹⁷ at each occurrence is independently selected from the group        consisting of: —H; optionally substituted C₁ to C₁₂ aliphatic;        an optionally substituted 3- to 14-membered carbocycle; and        optionally substituted 3-to 14-membered heterocycle,    -   each        (Z)_(p) group comprises a covalent linker “        ” containing one or more atoms selected from the group        consisting of C, O, N, S, and Si; “Z” is an activating        functional group having co-catalytic activity in epoxide CO₂        copolymerization, and p is an integer from 1 to 4 indicating the        number of individual activating functional groups Z present on a        given        (Z)_(p) group, Page 38 of 79    -   a is 1, 2, 3, or 4,    -   k is independently at each occurrence an integer from 1 to 8,        inclusive,    -   m is 0 or an integer from 1 to 8, inclusive,    -   q is 0 or an integer from 1 to 5, inclusive,    -   x is 0, 1, or 2, and    -   z is 1, 2, or 3.

In certain embodiments, of complexes 1 through 4,

is selected from the group consisting of a C₃₋₁₄ carbocycle, a C₆₋₁₀aryl group, a 3- to 14-membered heterocycle, and a 5- to 10-memberedheteroaryl group; a polyether group, or an optionally substituted C₂₋₂₀aliphatic group, wherein one or more methylene units are optionally andindependently replaced by —NR^(y)—, —N(R^(y))C(O)—, —C(O)N(R^(y))—,—OC(O)N(R^(y))—, —N(R^(y))C(O)O—, —OC(O)O—, —O—, —C(O)—, —OC(O)—,—C(O)O—, —S—, —SO—, —SO₂—, —C(═S)—, —C(═NR^(y))—, —C(═NOR^(y))— or—N═N—.

In some embodiments, one or more of the substituents on metal complexes1 through 9′ is an activating moiety

(Z)_(p), where “

” represents a covalent linker containing

one or more atoms selected from the group consisting of C, O, N, S, andSi; “Z” is an activating functional group having co-catalytic activityin epoxide CO₂ copolymerization, and p is an integer from 1 to 4indicating the number of individual activating functional groups presenton a given activating moiety.

In some embodiments, the one or more Z group(s) present on theactivating moiety is independently selected from the group consisting ofPPN⁺ derivatives (—PR₂═N⁺═PR₃); ammonium salts; phosphonium salts; or anoptionally substituted N-linked imidazolium, thiazolium, or oxazoliumgroup. In certain embodiments, a Z group is an optionally substitutedN-linked piperidine or N-linked pyrrolidine.

In some embodiments, a Z group is an optionally substituted guanidine.In other embodiments, a Z group is any of those described inWO2010022388. In certain embodiments, a Z-group is an amidine, andamidinium, a guanidine, a guanidinium, an optionally substitutedpyridinium, or an arsonium group.

In certain embodiments, a linker

may comprise a bond. In this case, the cationic functional group Z isbonded directly to the ligand. To avoid the need to arbitrarily definewhere a ligand ends and a tether begins, it is to be understood that ifa Z group is bonded directly to an atom that is typically regarded aspart of the parent structure of the ligand, then the linker

is to be regarded as comprising a bond. In certain embodiments, when

comprises a bond, b is 1.

In certain embodiments, each linker

contains 1-30 atoms including at least one carbon atom, and optionallyone or more atoms selected from the group consisting of N, O, S, Si, B,and P.

In certain embodiments, a linker is an optionally substituted C₂₋₃₀aliphatic group wherein one or more methylene units are optionally andindependently replaced by -Cy-, —NR^(y)—, —N(R^(y))C(O)—,—C(O)N(R^(y))—, —O—, —C(O)—, —OC(O)—, —C(O)O—, —S—, —SO—, —SO₂—,—C(═S)—, —C(═NR^(y))—, or —N═N—, wherein:

-   -   each —Cy— is independently an optionally substituted 5-8        membered bivalent, saturated, partially unsaturated, or aryl        ring having 0-4 heteroatoms independently selected from        nitrogen, oxygen, or sulfur, or an optionally substituted 8-10        membered bivalent saturated, partially unsaturated, or aryl        bicyclic ring having 0-5 heteroatoms independently selected from        nitrogen, oxygen, or sulfur; and    -   each R^(y) is independently —H, or an optionally substituted        radical selected from the group consisting of C₁₋₆ aliphatic,        phenyl, a 3-7 membered saturated or partially unsaturated        carbocyclic ring, a 3-7 membered saturated or partially        unsaturated monocyclic heterocyclic ring having 1-2 heteroatoms        independently selected from nitrogen, oxygen, or sulfur, a 5-6        membered heteroaryl ring having 1-3 heteroatoms independently        selected from nitrogen, oxygen, or sulfur, and 8- to 10-membered        aryl.

In certain embodiments, a linker

is a C₄-C₁₂ aliphatic group substituted with one or more moietiesselected from the group consisting of halogen, —NO₂, —CN, —SR^(y),—S(O)R^(y), —S(O)₂R^(y), —NR^(y)C(O)R^(y), —OC(O)R^(y), —CO₂R^(y), —NCO,—N₃, —OR⁴, —OC(O)N(R^(y))₂, —N(R^(y))₂, —NR^(y)C(O)R^(y), and—NR^(y)C(O)OR^(y), where each R^(y) and R⁴ is independently as definedabove and described in classes and subclasses herein.

In certain embodiments, a linker

is an optionally substituted C₃-C₃₀ aliphatic group. In certainembodiments, a linker is an optionally substituted C₄₋₂₄ aliphaticgroup. In certain embodiments, a linker moiety is an optionallysubstituted C₄-C₂₀ aliphatic group. In certain embodiments, a linkermoiety is an optionally substituted C₄-C₁₂ aliphatic group. In certainembodiments, a linker is an optionally substituted C₄₋₁₀ aliphaticgroup. In certain embodiments, a linker is an optionally substitutedC₄₋₈ aliphatic group. In certain embodiments, a linker moiety is anoptionally substituted C₄-C₆ aliphatic group. In certain embodiments, alinker moiety is an optionally substituted C₆-C₁₂ aliphatic group. Incertain embodiments, a linker moiety is an optionally substituted C₈aliphatic group. In certain embodiments, a linker moiety is anoptionally substituted C₇ aliphatic group. In certain embodiments, alinker moiety is an optionally substituted C₆ aliphatic group. Incertain embodiments, a linker moiety is an optionally substituted C₅aliphatic group. In certain embodiments, a linker moiety is anoptionally substituted C₄ aliphatic group. In certain embodiments, alinker moiety is an optionally substituted C₃ aliphatic group. Incertain embodiments, a aliphatic group in the linker moiety is anoptionally substituted straight alkyl chain. In certain embodiments, thealiphatic group is an optionally substituted branched alkyl chain. Insome embodiments, a linker moiety is a C₄ to C₂₀ alkyl group having oneor more methylene groups replaced by —C(R^(◯))₂— wherein R^(◯) is asdefined above. In certain embodiments, a linker

consists of a bivalent aliphatic group having 4 to 30 carbons includingone or more C₁₋₄ alkyl substituted carbon atoms. In certain embodiments,a linker moiety consists of a bivalent aliphatic group having 4 to 30carbons including one or more gem-dimethyl substituted carbon atoms.

In certain embodiments, a linker

includes one or more optionally substituted cyclic elements selectedfrom the group consisting of saturated or partially unsaturatedcarbocyclic, aryl, heterocyclic, or heteroaryl. In certain embodiments,a linker moiety consists of the substituted cyclic element, in someembodiments the cyclic element is part of a linker with one or morenon-ring heteroatoms or optionally substituted aliphatic groupscomprising other parts of the linker moiety.

In some embodiments, a linker moiety is of sufficient length to allow anatom bearing a positive (either wholly or through a resonance structure)within a cationic functional group to be positioned near a metal atom ofa metal complex. In certain embodiments, a linker moiety is ofsufficient length to allow an atom bearing a positive within a cationicfunctional group to be positioned within about 6 Å, within about 5 Å,within about 4 Å, within about 3.5 Å, or within about 3 Å. In certainembodiments, structural constraints are built into a linker moiety tocontrol the disposition and orientation of one or more cationicfunctional groups near a metal center of a metal complex. In certainembodiments, such structural constraints are selected from the groupconsisting of cyclic moieties, bicyclic moieties, bridged cyclicmoieties and tricyclic moieties. In some embodiments, such structuralconstraints are the result of acyclic steric interactions. In certainembodiments, steric interactions due to syn-pentane, gauche-butane,and/or allylic strain in a linker moiety, bring about structuralconstraints that affect the orientation of a linker and one or morecationic groups. In certain embodiments, structural constraints areselected from the group consisting of cis double bonds, trans doublebonds, cis allenes, trans allenes, and triple bonds. In someembodiments, structural constraints are selected from the groupconsisting of substituted carbons including geminally disubstitutedgroups such as sprirocyclic rings, gem dimethyl groups, gem diethylgroups and gem diphenyl groups. In certain embodiments, structuralconstraints are selected from the group consisting ofheteratom-containing functional groups such as sulfoxides, amides, andoximes.

In certain embodiments, linker moieties are selected from the groupconsisting of:

-   -   wherein each s is independently 0-6, t is 0-4, R^(y) as defined        above and described in classes and subclasses herein, *        represents the site of attachment to a ligand, and each        #represents a site of attachment of a Z group.

In some embodiments, s is 0. In some embodiments, s is 1. In someembodiments, s is 2. In some embodiments, s is 3. In some embodiments, sis 4. In some embodiments, s is 5. In some embodiments, s is 6.

In some embodiments, t is 1. In some embodiments, t is 2. In someembodiments, t is 3. In some embodiments, t is 4.

In some embodiments, provided metal complexes have a structure selectedfrom the group consisting of:

wherein:

-   -   M, L_(I), n, R¹, R^(1′), R², R^(2′), R³, R^(3′) and R¹¹ are as        defined above.

In some embodiments, a permanent ligand set is a salen ligand. Incertain embodiments, a metal complex is a metallosalenate. In certainembodiments, a metal complex is a cobalt salen complex. In certainembodiments, a metal complex is a chromium salen complex. In otherembodiments, a metal complex is an aluminum salen complex.

In certain embodiments, metal complexes of the present invention havethe formula:

wherein:

-   -   M is the metal atom;    -   L_(I) is a nucleophile capable of ring opening an epoxide;    -   n is an integer from 0-2 inclusive; and

is the permanent ligand set;

-   -   wherein        is as defined previously and each R′ independently represents        one or more substituents optionally present on the phenyl rings.

In certain embodiments, each R′ is independently an R^(d) group or a

(Z)_(p) group, where two or more adjacent R′ groups can be takentogether to form an optionally substituted saturated, partiallyunsaturated, or aromatic 3-to 12-membered ring containing 0 to 4heteroatoms,

In certain embodiments, the

moiety is selected from the group consisting of:

where

-   -   R^(c) and R′ are as previously defined,    -   Y is a divalent linker selected from the group consisting of:        —N(R¹¹)—; —O—; —S(O)_(x)—; —(CH₂)_(k)—; —C(O)—; —C(═NOR¹⁰)—;        —C(R^(c))_(x)H_(2-x)—; a polyether; an optionally substituted 3-        to 8-membered carbocycle; and an optionally substituted 3- to        8-membered heterocycle,    -   q is 0 or an integer from 1 to 5 inclusive, and    -   x is 0, 1, or 2,

In certain embodiments provided metal complexes have a structureselected from the group consisting of:

wherein:

-   -   M, R^(c), R′, L_(I), and n are as defined above;    -   R^(4a), R^(4a′), R^(5a), R^(5a′), R^(6a), R^(6a′), R^(7a), and        R^(7a′) are each independently hydrogen, a        (Z)_(p) group, halogen. —NO₂, —CN, —SR¹³, —S(O)R¹³, —S(O)₂R¹³,        —NR¹¹C(O)R¹³, —OC(O)R¹³, —CO₂R¹³, —NCO, —N₃, —OR¹⁰,        —OC(O)NR¹¹R¹², —Si(R¹³)₃, —NR¹¹R¹², —NR¹¹C(O)R¹³, and        —NR¹¹C(O)OR¹³; or an optionally substituted radical selected        from the group consisting of C₁₋₂₀ aliphatic; C₁₋₂₀        heteroaliphatic; 6- to 10-membered aryl; 5- to 10-membered        heteroaryl; and 3- to 7-membered heterocyclic, where [R^(1a) and        R^(4a)], [R^(1a′) and R^(4A′)] and any two adjacent R^(4a),        R^(4a′), R^(5a), R^(5a′), R^(6a), R^(6a′), R^(7a), and R^(7a′)        groups can be taken together with intervening atoms to form one        or more optionally substituted rings optionally containing one        or more heteroatoms;    -   n is 0 or an integer from 1 to 8, inclusive; and    -   p is 0 or an integer from 1 to 4, inclusive.

In some embodiments, R^(1a), R^(1a′), R^(4a), R^(4a′), R^(6a), andR^(6a′) are each —H. In some embodiments, R^(5a), R^(5a′), R^(7a) andR^(7a′) are each optionally substituted C₁-C₁₂ aliphatic. In someembodiments, R^(4a), R^(4a′), R^(5a), R^(5a′), R^(6a), R^(6a′), R^(7a),and R^(7a′) are each independently selected from the group consistingof: —H, —SiR₃; methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl,t-butyl, isoamyl, t-amyl, thexyl, and trityl. In some embodiments,R^(1a), R^(1a′), R^(4a), R^(4a′), R^(6a), and R^(6a′) are each —H. Insome embodiments, R^(7a) is selected from the group consisting of —H;methyl; ethyl; n-propyl; i-propyl; n-butyl; sec-butyl; t-butyl; isoamyl;t-amyl; thexyl; and trityl. In some embodiments, R^(5a) and R^(7a) areindependently selected from the group consisting of —H; methyl; ethyl;n-propyl; i-propyl; n-butyl; sec-butyl; t-butyl; isoamyl; t-amyl;thexyl; and trityl. In certain embodiments, one or more of R^(5a),R^(5a′), R^(7a) and R^(7a′) is a

(Z)_(p) group. In some embodiments, R^(5a) and R^(5a′) are each a

(Z)_(p) group. In some embodiments, R^(5a) is a

(Z)_(p) group and R^(5a′) is C₁₋₈ aliphatic. In some embodiments, R^(7a)and R^(7a′) are each a

(Z)_(p) group. In some embodiments, R^(7a) is a

(Z)_(p) group and R^(7a′) is C₁₋₈ aliphatic.

In certain embodiments, provided metal complexes have a structureselected from the group consisting of:

-   -   where R^(1a) through R^(7a′) are as defined above.

In certain embodiments, provided metal complexes have a structureselected from the group consisting of:

-   -   where R^(5a), R^(5a′), R^(7a), and R^(7a′) are as defined above.        In certain embodiments, each pair of substituents on the        salicaldehyde portions of the complexes above are the same (i.e.        R^(5a) & R^(5a′) are the same and R^(7a) & R^(7a′) are the        same). In other embodiments, at least one of R^(5a) & R^(5a′) or        R^(7a) & R^(7a) are different from one another.

In certain embodiments, a metal complex has formula III:

In certain embodiments, a metal complex has formula IV:

In certain embodiments, wherein a metal complex has formula V:

wherein:

-   -   R^(c), R^(d), L_(I), and q are as described above, and    -   R⁴, R^(4′), R⁵, R^(5′), R⁶, R^(6′), R⁷, and R^(7′) are each        independently selected from the group consisting of: —H; —R²⁰;        —R²¹; optionally substituted C₁-C₁₂ aliphatic; optionally        substituted 3- to 14-membered carbocycle; and optionally        substituted 3- to 14-membered heterocycle;    -   where [R¹ and R⁴], [R^(1′) and R^(4′)] and any two adjacent R⁴,        R^(4′), R⁵, R^(5′), R⁶, R^(6′), R⁷, and R^(7′) groups can        optionally be taken together with intervening atoms to form one        or more rings optionally substituted with one or more R²⁰        groups.

In certain embodiments, wherein a metal complex has formula III, R¹,R^(1′), R⁴, R^(4′), R⁶, and R^(6′) are each —H. In certain embodiments,wherein a metal complex has formula III, R⁵, R^(5′), R⁷ and R^(7′) areeach optionally substituted C₁-C₁₂ aliphatic.

In certain embodiments, wherein a metal complex has formula III, R⁴,R^(4′), R⁵, R^(5′), R⁶, R^(6′), R⁷, and R^(7′) are each independentlyselected from the group consisting of: —H, —Si(R¹³)₃; —Si[(CH₂)_(k)R²²]_(z)(R¹³)_((3-z)); methyl, ethyl, n-propyl, i-propyl,n-butyl, sec-butyl, t-butyl, isoamyl, t-amyl, thexyl, trityl,—C(CH₃)Ph₂, —(CH₂)_(p)C[(CH₂)_(p)R²²]_(z)H_((3-z)), and—Si(R¹³)_((3-z))[(CH₂)_(k)R²²]_(z), where p is an integer from 0 to 12inclusive and R²² is selected from the group consisting of: aheterocycle; an amine; a guanidine; —N⁺(R¹¹)₃ X⁻; —P⁺(R¹¹)₃X⁻;—P(R¹¹)₂═N⁺═P(R¹¹)₃ X⁻; —As⁺(R¹¹)₃ X⁻, and optionally substitutedpyridinium.

In certain embodiments, wherein a metal complex has formula III, R⁷ isselected from the group consisting of —H; methyl; ethyl; n-propyl;i-propyl; n-butyl; sec-butyl; t-butyl; isoamyl; t-amyl; thexyl; andtrityl; and R⁵ is selected from the group consisting of—(CH₂)_(p)CH_((3-z))[(CH₂)_(p)R²²]_(z) and—Si(R¹³)_((3-z))[(CH₂)_(k)R²²]_(z).

In certain embodiments, a metal complex has formula IV, R¹, R^(1′), R⁴,R^(4′), R⁶, and R^(6′)are each —H. In certain embodiments, wherein thecomplex is a metallosalenate complex of formula IV, R⁵, R^(5′), R⁷ andR^(7′) are each optionally substituted C₁-C₁₂ aliphatic.

In certain embodiments, wherein a metal complex has formula IV, R⁴,R^(4′), R⁵, R^(5′), R⁶, R^(6′), R⁷, and R^(7′) are each independentlyselected from the group consisting of: —H, —Si(R¹³)₃;—Si(R¹³)_((3-z))[(CH₂)_(k)R²²]_(z); methyl, ethyl, n-propyl, i-propyl,n-butyl, sec-butyl, t-butyl, isoamyl, t-amyl, thexyl, trityl,—(CH₂)_(p)C[(CH₂)_(p)R²²]_(z)H_((3-z)).

In certain embodiments, wherein a metal complex has formula IV, R⁷ isselected from the group consisting of —H; methyl; ethyl; n-propyl;i-propyl; n-butyl; sec-butyl; t-butyl; isoamyl; t-amyl; thexyl; andtrityl; and R⁵ is selected from the group consisting of—(CH₂)_(p)CH_((3-z))[(CH₂)_(p)R²²]_(z) and—Si(R¹³)_((3-z))[(CH₂)_(k)R²²]_(z).

In certain embodiments, wherein a metal complex has formula V, R¹,R^(1′), R⁴, R^(4′), R⁶, and R^(6′) are each —H. In certain embodiments,wherein a complex is a metallosalenate complex of formula V, R⁵, R^(5′),R⁷ and R^(7′) are each optionally substituted C₁-C₁₂ aliphatic.

In certain embodiments, wherein a metal complex has formula V, R⁴,R^(4′), R⁵, R^(5′), R⁶, R^(6′), R⁷, and R^(7′) are each independentlyselected from the group consisting of: —H, —Si(R¹³)₃; —Si[(CH₂)_(k)R²¹]_(z)(R¹³)_((3-z)); methyl, ethyl, n-propyl, i-propyl,n-butyl, sec-butyl, t-butyl, isoamyl, t-amyl, thexyl, trityl,—(CH₂)_(p)CH_((3-z))[(CH₂)_(p)R²²]_(z) and—Si(R¹³)_((3-z))[(CH₂)_(k)R²²]_(z).

In certain embodiments, wherein a metal complex has formula V, R⁷ isselected from the group consisting of —H; methyl; ethyl; n-propyl;i-propyl; n-butyl; sec-butyl; t-butyl; isoamyl; t-amyl; thexyl; andtrityl; and R⁵ is selected from the group consisting of—(CH₂)_(p)CH_((3-z))[(CH₂)_(p)R²²]_(z) and—Si(R¹³)_((3-z))[(CH₂)_(k)R²²]_(z).

In some embodiments, a metal complex has a structureL_(p)-M-(L_(I))_(n), where L_(p)-M is selected from the group consistingof:

In other embodiments, the permanent ligand set comprises a porphyrinring and L_(p)-M has the structure:

wherein:

-   -   M, L_(I), R^(c), and R^(d) are as defined above and any two        adjacent R^(c) or R^(d) groups can be taken together to form one        or more rings optionally substituted with one or more R²⁰ groups

In certain embodiments where the permanent ligand set comprises aporphyrin ring, M is a metal atom selected from the group consisting of:cobalt; chromium; aluminum; titanium; ruthenium, and manganese.

As noted above, in some embodiments herein, the permanent ligand set maycomprise a plurality of discrete ligands. In certain embodiments thepermanent ligand set includes two bidentate ligands. In certainembodiments, such bidentate ligands may have the structure

where R^(d) and R¹¹ are as defined hereinabove. Metal complexes havingtwo such ligands may adopt one of several geometries, and the presentdisclosure encompasses complex having any of the possible geometries, aswell as mixtures of two or more geometrical isomers.

In certain embodiments, metal complexes including two bidentate ligandsmay have structures selected from the group consisting of:

-   -   where each        represents a ligand:

I.a.3 Initiating Ligands

In addition to a metal atom and a permanent ligand set describedhereinabove, metal complexes suitable for polymerization systems of thepresent invention optionally include one or more initiating ligands-L_(I). In some embodiments, these ligands act as polymerizationinitiators and become a part of a growing polymer chain. In certainembodiments, there is one initiating ligand present (i.e. n=1). In otherembodiments, there are two initiating ligands present (i.e. n=2). Incertain embodiments, an initiating ligand may be absent (i.e. n=0). Incertain embodiments, a metal complex may be added to a reaction mixturewithout an initiating ligand, but may form a species in situ thatincludes one or two initiating ligands. In certain embodiments, aninitiating ligand contains a masked hydroxyl group.

In certain embodiments, -L_(I) is any anion. In certain embodiments,-L_(I) is a nucleophile. In some embodiments, initiating ligands -L_(I)are nucleophiles capable of ring-opening an epoxide. In someembodiments, a polymerization initiator L_(I) is selected from the groupconsisting of: azide, halides, alkyl sulfonates, carboxylates,alkoxides, and phenolates.

In some embodiments, initiating ligands include, but are not limited to,—OR^(x), —SR^(x), —OC(O)R^(x), —OC(O)OR^(x), —OC(O)N(R^(x))₂,—NR^(x)C(O)R^(x), —CN, halo (e.g., —Br, —I, —Cl), —N₃, and —OSO₂R^(x)wherein each R^(x) is, independently, selected from hydrogen, optionallysubstituted aliphatic, optionally substituted heteroaliphatic,optionally substituted aryl and optionally substituted heteroaryl andwhere two R^(x) groups can be taken together to form an optionallysubstituted ring optionally containing one or more additionalheteroatoms.

In some embodiments, metal complexes L_(p)-M-(L_(I))_(n), include one ormore initiating ligands -L_(I) characterized in that each ligand iscapable of initiating two or more polymer chains. In some embodiments,the initiating ligand is any of the molecules described above as beingsuitable as chain transfer agents. In certain embodiments, an initiatingligand is an anion derived from any of the chain transfer agentsdescribed hereinabove.

In some embodiments, polymerization systems of the present inventionfurther include at least one co-catalyst. In some embodiments, aco-catalyst is selected from the group consisting of: amines,guanidines, amidines, phosphines, nitrogen-containing heterocycles,ammonium salts, phosphonium salts, arsonium salts, bisphosphine ammoniumsalts, and a combination of any two or more of the above. In certainembodiments, a co-catalyst is covalently linked to the permanent ligandset of the metal complex.

In certain embodiments, polymerization systems comprise a catalyst andco-catalyst such that the initiating ligand on the metal complex and ananion present to balance the charge of a cationic co-catalyst are thesame molecule.

In embodiments where the co-catalyst is an ‘onium’ salt, there isnecessarily an anion present to balance the charge of the salt. Incertain embodiments, this is any anion. In certain embodiments, theanion is a nucleophile. In some embodiments, the anion is a nucleophilecapable of ring-opening an epoxide. In some embodiments, the anion isselected from the group consisting of: azide, halides, alkyl sulfonates,carboxylates, alkoxides, and phenolates. In certain embodiments, aco-catalyst anion contains a masked hydroxyl group.

In some embodiments, ionic co-catalyst include anions selected from thegroup consisting of: —OR^(x), —SR^(x), —OC(O)R^(x), —OC(O)OR^(x),—OC(O)N(R^(x))₂, —NR^(x)C(O)R^(x), —CN, halo (e.g., —Br, —I, —Cl), —N₃,and —OSO₂R^(x) wherein each R^(x) is, independently, selected fromhydrogen, optionally substituted aliphatic, optionally substitutedheteroaliphatic, optionally substituted aryl and optionally substitutedheteroaryl and where two R^(x) groups can be taken together to form anoptionally substituted ring optionally containing one or more additionalheteroatoms.

In certain embodiments, a co-catalyst anion is —OC(O)R^(x), whereinR^(x) is selected from optionally substituted aliphatic, fluorinatedaliphatic, optionally substituted heteroaliphatic, optionallysubstituted aryl, fluorinated aryl, and optionally substitutedheteroaryl.

In certain embodiments, a co-catalyst anion is —OC(O)R^(x), whereinR^(x) is optionally substituted aliphatic. In certain embodiments, aco-catalyst anion is —OC(O)R^(x), wherein R^(x) is optionallysubstituted alkyl and fluoroalkyl. In certain embodiments, a co-catalystanion is —OC(O)CH₃ or —OC(O)CF₃.

Furthermore, in certain embodiments, a co-catalyst anion is —OC(O)R^(x),wherein R^(x) is optionally substituted aryl, fluoroaryl, or heteroaryl.In certain embodiments, a co-catalyst anion is —OC(O)R^(x), whereinR^(x) is optionally substituted aryl. In certain embodiments, aco-catalyst anion is —OC(O)R^(x), wherein R^(x) is optionallysubstituted phenyl. In certain embodiments, a co-catalyst anion is—OC(O)C₆H₅ or —OC(O)C₆F₅.

In certain embodiments, a co-catalyst anion is —OR^(x), wherein R^(x) isselected from optionally substituted aliphatic, optionally substitutedheteroaliphatic, optionally substituted aryl, and optionally substitutedheteroaryl.

For example, in certain embodiments, a co-catalyst anion is —OR^(x),wherein R^(x) is optionally substituted aryl. In certain embodiments, aco-catalyst anion is —OR^(x), wherein R^(x) is optionally substitutedphenyl. In certain embodiments, a co-catalyst anion is —OC₆H₅ or—OC₆H₂(2,4-NO₂).

In certain embodiments, a co-catalyst anion is halo. In certainembodiments, a co-catalyst anion is —Br. In certain embodiments, aco-catalyst anion is —Cl. In certain embodiments, a co-catalyst anion is—I.

In certain embodiments, a co-catalyst anion is —O(SO₂)R^(x). In certainembodiments a co-catalyst anion is —OTs. In certain embodiments aco-catalyst anion is —OSO₂Me. In certain embodiments a co-catalyst anionis —OSO₂CF₃. In some embodiments, a co-catalyst anion is a2,4-dinitrophenolate anion.

In certain embodiments, polymerization systems of the present inventioninclude a cationic co-catalyst having a counterion characterized in thatthe counterion is capable of initiating polymerization at two or moresites. In some embodiments, a counterion is any of the moleculesdescribed above as being suitable as initiating ligands (L_(I)). Incertain embodiments, an anion is derived from any of the chain transferagents described hereinabove.

Ic. Stoichiometry of the Polymerization Systems

Having described in detail each of the components of the polymerizationsystem, we turn now to the relative ratios of those components. Incertain embodiments, a metal complex L_(p)-M-(L_(I))_(n) and a chaintransfer agent Y-A-(Y)_(n′) are present in a defined ratio selected tomaximize conversion of the epoxide monomers while achieving the desiredmolecular weight polycarbonate polyol. In embodiments, where aco-catalyst is present, the ratios between a metal complex, aco-catalyst and a chain transfer agent are selected to maximizeconversion of the epoxide monomers while achieving the desired molecularweight polycarbonate polyol.

In some embodiments, a metal complex and a chain transfer agent arepresent in a molar ratio greater than 1:10. In some embodiments, a metalcomplex and a chain transfer agent are present in a molar ratio greaterthan 1:100. In some embodiments, a metal complex and a chain transferagent are present in a molar ratio greater than 1:1000. In someembodiments, a metal complex and a chain transfer agent are present in amolar ratio ranging from about 1:10 to about 1:1000. In someembodiments, a metal complex and a chain transfer agent are present in amolar ratio ranging from about 1:10 to about 1:10000. In certainembodiments, the ratio is between about 1:1000 and about 1:5000. Incertain embodiments, the ratio is between about 1:1000 and about 1:3000.In certain embodiments, the ratio is between about 1:1000 and about1:2000. In certain embodiments, the ratio is between about 1:2000 andabout 1:4000. In certain embodiments, the ratio is between about 1:50and about 1:5000. In certain embodiments, the ratio is between about1:50 and about 1:1000. In certain embodiments, the ratio is betweenabout 1:250 and about 1:1000. In certain embodiments, the ratio isbetween about 1:50 and about 1:500. In certain embodiments, the ratio isbetween about 1:20 and about 1:500. In certain embodiments, the ratio isbetween about 1:50 and about 1:250. In certain embodiments, the ratio isbetween about 1:20 and about 1:100. In certain embodiments, the ratio isbetween about 1:100 and about 1:250. In some embodiments, a metalcomplex and a chain transfer agent are present in a molar ratio lessthan 1:1000.

In some embodiments, a metal complex and a co-catalyst are present in amolar ratio ranging from about 0.1:1 to about 1:10. In certainembodiments, the ratio is from about 0.5:1 to about 5:1. In otherembodiments, the ratio is from about 1:1 to about 4:1. In certainembodiments the ratio between the metal complex and the co-catalyst isabout 1:1. In other embodiments, the molar ratio between a metal complexand a co-catalyst is about 1:2.

It is generally desirable to maintain the concentration of a metalcomplex in a polymerization at a low level relative to the epoxide. Incertain embodiments, the molar ratio of metal complex to epoxide rangesfrom about 1:100 to about 1:1,000,000. In certain embodiments, the ratioranges from about 1:5,000 to about 1:500,000. In some embodiments, theratio ranges from about 1:10,000 to about 1:200,000. In otherembodiments, the ratio ranges from about 1:20,000 to about 1:100,000.

II. Polycarbonate Polyol Compositions

As described above, there have not been methods heretofore available toproduce aliphatic polycarbonate polyol resins combining the features ofhigh carbonate linkage content, a high percentage of hydroxyl end groupsand low molecular weight (e.g. less than about 20 kg/mol), and whereinsubstantially all polycarbonate chains having hydroxyl end groups haveno embedded chain transfer agent. In one aspect, the present inventionencompasses these novel materials.

In certain embodiments, such materials conform to a structure:

-   -   where each of R²³, and R²⁴ is independently selected from the        group consisting of: —H; and an optionally substituted group        selected from C₁₋₃₀ aliphatic; C₆₋₁₄ aryl; 3- to 12-membered        heterocycle, and 5- to 12-membered heteroaryl, where any two or        more of R²³ and R²⁴ can be taken together with intervening atoms        to form one or more optionally substituted 3- to 12-membered        rings, optionally containing one or more heteroatoms.

As used herein, the term “substantially all” means nearly all, or all toa measurable extent. In some embodiments, “substantially all” refers toat least 95%, at least 96%, at least 97%, at least 98%, at least 99%, orat least 99.9%.

In some embodiments, the present invention encompasses epoxide CO₂copolymers with a molecular weight number between about 400 and about20,000 characterized in that the polymer chains have a carbonate contentof >90%, and at least 90% of the end groups are hydroxyl groups, andwherein substantially all polycarbonate chains having hydroxyl endgroups have no embedded chain transfer agent. In some embodiments, atleast 95% of the end groups of the polycarbonate polyol are OH groups.In some embodiments, at least 97% of the end groups of the polycarbonatepolyol are OH groups. In some embodiments, at least 98% of the endgroups of the polycarbonate polyol are OH groups. In some embodiments,at least 99% of the end groups of the polycarbonate polyol are OHgroups.

In certain embodiments, the present invention comprises novelcompositions of matter comprising hydroxyl-terminated aliphaticpolycarbonate chains with a fragment attached to one end of thecarbonate where the fragment also comprises a hydroxyl group.

In certain embodiments, such materials conform to a structure Q1:

-   -   where each of -A-, R²³, and R²⁴ is as defined above and in the        classes and subclasses herein.

For example, if a polymer of the present invention were made bycopolymerization of propylene oxide and CO₂ with mono-OH-protected1,4-butanediol as the chain transfer agent, then, for the resultingpolymer of formula Q1, R²³ would be —H, R²⁴ would be —CH₃, (or viceversa), -A- would be —(CH₂)₄—, and the polymer would have the structure:

The other polymers encompasses by the present invention can beapprehended by considering the analogous materials resulting from thecopolymerization of any one or more of the epoxides described hereinwith CO₂ in the presence of the chain transfer agents Y-A-(Y)_(n′)described above. The present invention contemplates all of thesecombinations and variations individually and in combination.

In certain embodiments, the carbonate linkage content of thepolycarbonate chains of epoxide CO₂ copolymers of the present inventionis at least 90%. In some embodiments greater than 92% of linkages arecarbonate linkages. In certain embodiments, at least 95% of linkages arecarbonate linkages. In certain embodiments, at least 97% of linkages arecarbonate linkages. In some embodiments, greater than 98% of linkagesare carbonate linkages in some embodiments at least 99% of linkages arecarbonate linkages. In some embodiments essentially all of the linkagesare carbonate linkages (i.e. there are essentially only carbonatelinkages detectable by typical methods such as ¹H or ¹³C NMRspectroscopy).

In certain embodiments, the ether linkage content of the polycarbonatechains of epoxide CO₂ copolymers of the present invention is less than10%. In some embodiments, less than 8% of linkages are ether linkages.In certain embodiments, less than 5% of linkages are ether linkages. Incertain embodiments, no more than 3% of linkages are ether linkages. Insome embodiments, fewer than 2% of linkages are ether linkages in someembodiments less than 1% of linkages are ether linkages. In someembodiments essentially none of the linkages are ether linkages (i.e.there are essentially no ether bonds detectable by typical methods suchas ¹H or ¹³C NMR spectroscopoy).

In some embodiments, the epoxide CO₂ copolymers of the present inventionhave average molecular weight numbers ranging from about 400 to about400,000 g/mol. In some embodiments, the epoxide CO₂ copolymers of thepresent invention have average molecular weight numbers ranging fromabout 300 to about 20,000 g/mol. In some embodiments, the epoxide CO₂copolymers of the present invention have average molecular weightnumbers ranging from about 400 to about 20,000 g/mol. In someembodiments, the copolymers have an Mn between about 500 and about15,000 g/mol. In some embodiments, the copolymers have an Mn betweenabout 500 and about 5,000 g/mol. In some embodiments, the copolymershave an Mn between about 500 and about 1,500 g/mol. In otherembodiments, the copolymers have an Mn between about 800 and about 4,000g/mol. In other embodiments, the copolymers have an Mn between about 800and about 5,000 g/mol. In some embodiments, the copolymers have an Mnbetween about 1,000 and about 3,000 g/mol. In some embodiments, thecopolymers have an Mn of about 700 g/mol. In some embodiments, thecopolymers have an Mn of about 1,000 g/mol. In some embodiments, thecopolymers have an Mn of about 2,000 g/mol. In some embodiments, thecopolymers have an Mn of about 3,000 g/mol. In some embodiments, thecopolymers have an Mn of about 4,000 g/mol. In some embodiments, thecopolymers have an Mn of about 5,000 g/mol. In some embodiments, thecopolymers have an Mn of about 6,000 g/mol. In some embodiments, thecopolymers have an Mn of about 7,000 g/mol. In some embodiments, thecopolymers have an Mn of about 8,000 g/mol. In certain embodiments,epoxide CO₂ copolymers of the invention have about 10 to about 200repeat units. In other embodiments, the copolymers have about 20 toabout 100 repeat units.

In some embodiments, the CO₂ epoxide copolymers of the present inventionare formed from CO₂ and one type of epoxide. In other embodiments, thecopolymers incorporate two or more types of epoxide. In someembodiments, the copolymers predominantly incorporate one epoxide withlesser amounts of one or more additional epoxides. In certainembodiments where two or more epoxides are present, the copolymer israndom with respect to the position of the epoxide moieties within thechain. In other embodiments where two or more epoxides are present, thecopolymer is a tapered copolymer with respect to the incorporation ofdifferent epoxides. In some embodiments where two or more epoxides arepresent, the copolymer is a block copolymer with respect to theincorporation of different epoxides.

In certain embodiments, polycarbonate polyols of the present inventionare further characterized in that they have narrow polydispersity. Incertain embodiments, the PDI of the provided polymer compositions isless than 2. In some embodiments, the PDI is less than 1.6. In someembodiments, the PDI is less than 1.5. In other embodiments, the PDI isless than about 1.4. In certain embodiments, the PDI is less than about1.2. In other embodiments, the PDI is less than about 1.1. In certainembodiments, the polycarbonate polyol compositions are furthercharacterized in that they have a unimoldal molecular weightdistribution.

In certain embodiments, the polycarbonate polyols of the presentinvention contain repeat units derived from epoxides that are not C2symmetric. In these cases, the epoxide can be incorporated into thegrowing polymer chain in one of several orientations. The regiochemistryof the enchainment of adjacent monomers in such cases is characterizedby the head-to-tail ratio of the composition. As used herein the term“head-to-tail” refers to the regiochemistry of the enchainment of asubstituted epoxide in the polymer chain as shown in the figure belowfor propylene oxide:

In certain embodiments the disclosure encompasses polycarbonate polyolcompositions characterized in that, on average, more than about 80% oflinkages between adjacent epoxide monomer units are head-to-taillinkages. In certain embodiments, on average, more than 85% of linkagesbetween adjacent epoxide monomer units are head-to-tail linkages. Incertain embodiments, on average, more than 90% of linkages betweenadjacent epoxide monomer units are head-to-tail linkages. In certainembodiments, more than 95% of linkages between adjacent epoxide monomerunits are head-to-tail linkages. In certain embodiments, more than 99%of linkages between adjacent epoxide monomer units are head-to-taillinkages.

In certain embodiments, the polycarbonate polyols of the presentinvention contain repeat units derived from epoxides that contain achiral center. In these cases, the epoxide can be incorporated into thegrowing polymer chain in defined orientations relative to adjacentmonomer units. In certain embodiments, the adjacent stereocenters arearranged randomly within the polymer chains. In certain embodiments, thepolycarbonate polyols of the present invention are atactic. In otherembodiments, more than about 60% of adjacent monomer units have the samestereochemistry. In certain embodiments, more than about 75% of adjacentmonomer units have the same stereochemistry. In certain embodiments,more than about 85% of adjacent monomer units have the samestereochemistry. In certain embodiments, more than about 95% of adjacentmonomer units have the same stereochemistry. In certain embodiments thepolycarbonate polyols of the present invention are isotactic. In otherembodiments, more than about 60% of adjacent monomer units have theopposite stereochemistry. In certain embodiments, more than about 75% ofadjacent monomer units have the opposite stereochemistry. In certainembodiments, more than about 85% of adjacent monomer units have theopposite stereochemistry. In certain embodiments, more than about 95% ofadjacent monomer units have the opposite stereochemistry. In certainembodiments the polycarbonate polyols of the present invention aresyndiotactic.

In certain embodiments, where a chiral epoxide is incorporated into thepolycarbonate polyol compositions of the present invention, the polymersare enantio-enriched. In other embodiments, where a chiral epoxide isincorporated into the polycarbonate polyol compositions of the presentinvention, the polymers are not enantio-enriched.

In certain embodiments, the epoxide monomers incorporated intopolycarbonate polyols of the present invention have a structure:

-   -   where, R²², R²³, R²⁴, and R²⁵ are each independently selected        from the group consisting of: —H; and an optionally substituted        group selected from C₁₋₃₀ aliphatic; C₆₋₁₄ aryl; 3- to        12-membered heterocycle, and 5- to 12-membered heteroaryl, where        any two or more of R²², R²³, R²⁴, and R²⁵ can be taken together        with intervening atoms to form one or more optionally        substituted 3- to 12-membered rings, optionally containing one        or more heteroatoms.

In certain embodiments, the polycarbonate polyols of the presentinvention incorporate one or more epoxides selected from the groupconsisting of:

wherein each R^(x) is, independently, selected from optionallysubstituted aliphatic, optionally substituted heteroaliphatic,optionally substituted aryl fluoroalkyl, and optionally substitutedheteroaryl.

In certain embodiments, an epoxide is ethylene oxide. In otherembodiments, an epoxide is propylene oxide. In other embodiments, anepoxide is cyclohexene oxide. In other embodiments, an epoxide isepichlorohydrin. In certain embodiments, epoxide monomers selectedinclude glycidyl ether or glycidyl ester. In certain embodiments,epoxide monomers selected include phenyl glycidyl ether. In certainembodiments, epoxide monomers selected include t-butyl glycidyl ether.In certain embodiments, epoxide monomers selected include ethylene oxideand propylene oxide.

In certain embodiments, polycarbonate polyols of the present inventioncomprise poly(ethylene carbonate). In other embodiments, polycarbonatepolyols of the present invention comprise poly(propylene carbonate). Inother embodiments, polycarbonate polyols of the present inventioncomprise poly(cyclohexene carbonate). In other embodiments,polycarbonate polyols of the present invention comprisepoly(epichlorohydrin carbonate). In certain embodiments, polycarbonatepolyols of the present invention incorporate a glycidyl ether orglycidyl ester. In certain embodiments, polycarbonate polyols of thepresent invention incorporate phenyl glycidyl ether. In certainembodiments, polycarbonate polyols of the present invention incorporatet-butyl glycidyl ether.

In certain embodiments, epoxides are derived from naturally occurringmaterials such as epoxidized resins or oils. Examples of such epoxidesinclude, but are not limited to: Epoxidized Soybean Oil; EpoxidizedLinseed Oil; Epoxidized Octyl Soyate; Epoxidized PGDO; Methyl EpoxySoyate; Butyl Epoxy Soyate; Epoxidized Octyl Soyate; Methyl EpoxyLinseedate; Butyl Epoxy Linseedate; and Octyl Epoxy Linseedate. Theseand similar materials are available commercially from Arkema Inc. underthe trade name Vikoflex®. Examples of such commerically availableVikoflex® materials include Vikoflex 7170 Epoxidized Soybean Oil,Vikoflex 7190 Epoxidized Linseed, Vikoflex 4050 Epoxidized Octyl Soyate,Vikoflex 5075 Epoxidized PGDO, Vikoflex 7010 Methyl Epoxy Soyate,Vikoflex 7040 Butyl Epoxy Soyate, Vikoflex 7080 Epoxidized Octyl Soyate,Vikoflex 9010 Methyl Epoxy Linseedate, Vikoflex 9040 Butyl EpoxyLinseedate, and Vikoflex 9080 Octyl Epoxy Linseedate. In certainembodiments, the polycarbonate polyols of the present inventionincorporate epoxidized fatty acids.

In certain embodiments, epoxides are derived from alpha olefins.Examples of such epoxides include, but are not limited to those derivedfrom C₁₀ alpha olefin, C₁₂ alpha olefin, C₁₄ alpha olefin, C₁₆ alphaolefin, C₁₈ alpha olefin, C₂₀-C₂₄ alpha olefin, C₂₄-C₂₈ alpha olefin andC₃₀₊ alpha olefins. These and similar materials are commerciallyavailable from Arkema Inc. under the trade name Vikolox®. In certainembodiments, epoxide mixtures including alpha olefins also include othersimpler epoxide monomers including, but not limited to: ethylene oxide,propylene oxide, butylene oxide, hexene oxide, cyclopentene oxide andcyclohexene oxide.

In some embodiments, polycarbonate polyols of the present inventioncomprise poly(propylene-co-ethylene carbonate). In certain embodiments,polycarbonate polyols of the present invention comprise poly(propylenecarbonate) incorporating from about 0.1 to about 10% of a C₄-C₃₀epoxide. In certain embodiments, polycarbonate polyols of the presentinvention comprise poly(propylene carbonate) incorporating from about0.1 to about 10% of a glycidyl ether. In certain embodiments,polycarbonate polyols of the present invention comprise poly(propylenecarbonate) incorporating from about 0.1 to about 10% of a glycidylester. In certain embodiments, polycarbonate polyols of the presentinvention comprise poly(ethylene carbonate) incorporating from about 0.1to about 10% of a glycidyl ether. In certain embodiments, polycarbonatepolyols of the present invention comprise poly(ethylene carbonate)incorporating from about 0.1 to about 10% of a glycidyl ester. Incertain embodiments, polycarbonate polyols of the present inventioncomprise poly(ethylene carbonate) incorporating from about 0.1 to about10% of a C₄-C₃₀ epoxide.

In certain embodiments, epoxide monomers incorporated into polycarbonatepolyols of the present invention include epoxides derived from naturallyoccurring materials such as epoxidized resins or oils. In certainembodiments of the present invention, polycarbonate polyols of thepresent invention incorporate epoxides derived from alpha olefins.

In another aspect, the present invention encompasses materials made bycross-linking any of the above polycarbonate polyol polymers. In certainembodiments, such cross-linked materials comprise polyurethanes. Incertain embodiments such polyurethanes encompass thermoplastics, foams,coatings and adhesives.

III. Methods of Making Polycarbonate Polyols

In a third aspect, the present invention encompasses methods forproducing polycarbonate polyols.

In some embodiments, the method includes the steps of:

-   -   a) contacting a reaction mixture comprising one or more epoxides        with a polymerization system as described herein in the presence        of carbon dioxide;    -   b) allowing the polymerization reaction to proceed until a        desired molecular weight aliphatic polycarbonate polyol has        formed,    -   c) terminating the polymerization; and    -   d) treating the aliphatic polycarbonate polyol under suitable        conditions to unmask the one or more masked hydroxyl groups,        wherein the one or more masked hydroxyl groups are hydroxyl        protecting groups or latent hydroxyl groups.        III.a. Epoxides

In some embodiments, epoxide monomers provided at step (a) include anyof the epoxides described hereinabove with regard to the polymercompositions of matter.

III.b. Chain Transfer Agents

In certain embodiments, a chain transfer agent provided in thepolymerization system of step (a) of the above method is any of thechain transfer agents described hereinabove or mixtures of two or moreof these.

III.b.1. Removal of Masked Hydroxyl Groups

As described above, in certain embodiments masked hydroxyl groups areprotected hydroxyl groups. Deprotection chemistries for protectinggroups are known in the art and are familiar to the skilled artisan.Without wishing to be bound by any particular theory, it is believedthat particular deprotection conditions are advantageous in the contextof polycarbonates, for example thermal, hydrogenating, acidicconditions, or a combination thereof. In some embodiments, the skilledartisan will select an appropriate protecting group such thatdeprotection may be achieved while maintaining the integrity of thepolycarbonate polymer.

In some embodiments, a protecting group is removed under acidicconditions. In some embodiments, acidic conditions are aqueous. In someembodiments, acidic conditions are non-aqueous. In some embodiments,acidic conditions comprise an inorganic acid, an organic acid, and/or aLewis acid. In some embodiments, acidic conditions comprise heat.

In some embodiments, a protecting group is removed under thermalconditions. In some embodiments, thermal conditions comprise heating tosolvent reflux temperature. In some embodiments, thermal conditionscomprise heating to 50° C. or above. In some embodiments, thermalconditions comprise heating to 75° C. or above. In some embodiments,thermal conditions comprise heating to 100° C. or above. In someembodiments, thermal conditions comprise heating to 150° C. or above.

In some embodiments, a protecting group is removed under hydrogenatingconditions. in some embodiments, hydrogenating conditions comprisehydrogen gas and Raney nickel. In some embodiments, hydrogenatingconditions comprise hydrogen gas and platinum. In some embodiments,hydrogenating conditions comprise hydrogen gas and palladium. In someembodiments, hydrogenating conditions comprise hydrogen gas and Lindlarcatalyst. In some embodiments, hydrogenating conditions comprisehydrogen gas and rhodium. In some embodiments, hydrogenating conditionscomprise heat. In some embodiments, hydrogenating conditions compriseacidic pH. In some embodiments, hydrogenating conditions comprisehydrazine.

In some embodiments, the conditions described above for removing aprotecting group are useful for exposing a latent hydroxyl group. Inother embodiments, a latent hydroxyl group is exposed not by removingwhat would be consider a traditional protecting group, but rather byconverting a functional group to a hydroxyl group. Such conversions tohydroxyl groups are known in the art, and any available technique knownin the art can be applied to latent hydroxyl groups. See, for example,March, supra.

In certain embodiments, a latent hydroxyl group is created by hydrolysisof an alkyl halide, a carboxylic ester, an inorganic ester, an orthoester, or a sulfonic ester. In certain embodiments, a latent hydroxylgroup is created by reduction of a carboxylic ester group, using lithiumaluminum hydride or another suitable reducing agent (see March, supra).In some embodiments, a latent hydroxyl group is created by oxidation ofan alkene or borane (see March, supra).

III.c. Polymerization Catalysts

In some embodiments, a provided metal complex is a polymerizationcatalyst. In certain embodiments, a polymerization catalyst with whichthe reaction mixture is contacted in the polymerization system of step(a) of the above-described method include any one or more of thecatalysts previously described herein.

III.d. Co-Catalysts

In some embodiments, methods of the present invention include the use ofat least one co-catalyst. In some embodiments, a co-catalyst is presentat step (b). In certain embodiments, a co-catalyst is any one or more ofthe co-catalytic species described above in the description of thepolymerization systems of the present invention.

III.e. Reaction Conditions

In certain embodiments, the steps of any of the above methods furthercomprise one or more solvents. In certain other embodiments, thepolymerization steps are performed in neat epoxide without the additionof solvent.

In certain methods, where a polymerization solvent is present, thesolvent is an organic solvent. In certain embodiments, the solvent is ahydrocarbon. In certain embodiments, the solvent is an aromatichydrocarbon. In certain embodiments, the solvent is an aliphatichydrocarbon. In certain embodiments, the solvent is a halogenatedhydrocarbon.

In certain embodiments, the solvent is an ether. In certain embodiments,the solvent is an ester. In certain embodiments the solvent is a ketone.

In certain embodiments suitable solvents include, but are not limitedto: Methylene Chloride, Chloroform, 1,2-Dichloroethane, PropyleneCarbonate, Acetonitrile, Dimethylformamide, N-Methyl-2-pyrrolidone,Dimethyl Sulfoxide, Nitromethane, Caprolactone, 1,4-Dioxane, and1,3-Dioxane.

In certain other embodiments, suitable solvents include, but are notlimited to: Methyl Acetate, Ethyl Acetate, Acetone, Methyl Ethyl Ketone,Propylene Oxide, Tretrahydrofuran, Monoglyme Triglyme, Propionitrile,1-Nitropropane, Cyclohexanone.

In certain embodiments, any of the above methods comprise aliphaticoxide present in amounts concentrations between about 0.5 M to about 20M or the neat concentration of the aliphatic oxide. In certainembodiments, aliphatic oxide is present in amounts between about 0.5 Mto about 2 M. In certain embodiments, aliphatic oxide is present inamounts between about 2 M to about 5 M. In certain embodiments,aliphatic oxide is present in amounts between about 5 M to about 20 M.In certain embodiments, aliphatic oxide is present in an amount of about20 M. In certain embodiments, liquid aliphatic oxide comprises thereaction solvent.

In certain embodiments, CO₂ is present at a pressure of between about 30psi to about 800 psi. In certain embodiments, CO₂ is present at apressure of between about 30 psi to about 500 psi. In certainembodiments, CO₂ is present at a pressure of between about 30 psi toabout 400 psi. In certain embodiments, CO₂ is present at a pressure ofbetween about 30 psi to about 300 psi. In certain embodiments, CO₂ ispresent at a pressure of between about 30 psi to about 200 psi. Incertain embodiments, CO₂ is present at a pressure of between about 30psi to about 100 psi. In certain embodiments, CO₂ is present at apressure of between about 30 psi to about 80 psi. In certainembodiments, CO₂ is present at a pressure of about 30 psi. In certainembodiments, CO₂ is present at a pressure of about 50 psi. In certainembodiments, CO₂ is present at a pressure of about 100 psi. In certainembodiments, the CO₂ is supercritical.

In certain embodiments of the above methods the reaction is conducted ata temperature of between about 0° C. to about 150° C. In certainembodiments, the reaction is conducted at a temperature of between about23° C. to about 100° C. In certain embodiments, the reaction isconducted at a temperature of between about 23° C. and about 80° C. Incertain embodiments, the reaction to be conducted at a temperature ofbetween about 23° C. to about 50° C.

In certain embodiments, a polymerization step of any of the abovemethods produces cyclic carbonate as a by-product in amounts of lessthan about 20%. In certain embodiments, cyclic carbonate is produced asa by-product in amounts of less than about 15%. In certain embodiments,cyclic carbonate is produced as a by-product in amounts of less thanabout 10%. In certain embodiments, cyclic carbonate is produced as aby-product in amounts of less than about 5%. In certain embodiments,cyclic carbonate is produced as a by-product in amounts of less thanabout 1%. In certain embodiments, the reaction does not produce anydetectable by-products (e.g., as detectable by ¹H-NMR and/or liquidchromatography (LC)).

In certain embodiments, a polymerization time is between about 30minutes and about 48 hours. In some embodiments, the reaction is allowedto process for less than 24 hours. In some embodiments, the reaction isallowed to progress for less than 12 hours. In some embodiments, thereaction is allowed to process for between about 4 and about 12 hours.

In certain embodiments, a polymerization reaction is allowed to proceeduntil the number average molecular weight of the polymers formed is thatof the average molecular weights described herein for polycarbonatepolyol compositions.

In certain embodiments, provided methods further include the step ofsampling the reaction and determining the molecular weight of thepolymer at a given time. In certain embodiments, this sampling andmolecular weight determination are performed at two or more timeintervals. In certain embodiments a plot of molecular weight gain overtime is constructed and the method further includes the step ofdetermining from this plot the time at which a desired molecular weightpolymer will be present. In certain embodiments, the time at which thepolymerization is ended is determined by this method.

In certain embodiments, a polymerization reaction proceeds until betweenabout 20% and about 100% of the provided epoxide is consumed. In certainembodiments, the conversion is between about 40% and about 90%. Incertain embodiments, the conversion is at least 50%. In otherembodiments, the conversion is at least 60%, at least 80% or at least85%. In certain embodiments, at least 80% of the provided epoxide isconverted to polymer.

IV. Higher Polymers

The present disclosure encompasses higher polymers derived from thepolycarbonate polyols described hereinabove. In certain embodiments,such higher polymers are formed by reacting the polyols with suitablecross-linking agents. Examples of higher polymers that may be made usingthe polyols of the present invention as well as suitable reagents,conditions, processing methods and formulations are disclosed in WO2011/163250.

In certain embodiments, cross linkers including functional groupsreactive toward hydroxyl groups are selected, for example, from epoxyand isocyanate groups. In certain embodiments, such cross linking agentsare polyisocyanates.

In some embodiments, a difunctional or higher-functionality isocyanateis selected from di-isocyanates, the biurets and cyanurates ofdiisocyanates, and the adducts of diisocyanates to polyols. Suitablediisocyanates have generally from 4 to 22 carbon atoms. Thediisocyanates are typically selected from aliphatic, cycloaliphatic andaromatic diisocyanates, for example 1,4-diisocyanatobutane,1,6-diisocyanatohexane, 1,6-diisocyanato-2,2,4-trimethylhexane,1,6-diisocyanato-2,4,4-trimethylhexane, 1,2-, 1,3- and1,4-diisocyanatocyclohexane, 2,4- and2,6-diisocyanato-1-methylcyclohexane,4,4′-bis(isocyanatocyclohexyl)methane, isophorone diisocyanate(=1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane), 2,4- and2,6-tolylene diisocyanate, tetramethylene-p-xylylene diisocyanate(=1,4-bis(2-isocyanatoprop-2-yl)benzene),4,4′-diisocyanatodiphenylmethane, preferably 1,6-diisocyanatohexanediisocyanatohexane and isophorone diisocyanate, and mixtures thereof.

In certain embodiments, crosslinking compounds comprise the cyanuratesand biurets of aliphatic diisocyanates. In certain embodiments,crosslinking compounds are the di-isocyanurate and the biuret ofisophorone diisocyanate, and the isocyanate and the biuret of1,6-diisocyanatohexane. Examples of adducts of diisocyanates to polyolsare the adducts of the abovementioned diisocyanates to glycerol,trimethylolethane and trimethylolpropane, for example the adduct oftolylene diisocyanates to trimethylolpropane, or the adducts of1,6-diisocyanatohexane or isophorone diisocyanate to trimethylpropaneand/or glycerol.

In some embodiments, a polyisocyanate used, may, for example, be anaromatic polyisocyanate such as tolylene diisocyanate, diphenylmethanediisocyanate or polymethylene polyphenyl isocyanate, an aliphaticpolyisocyanate such as hexamethylene diisocyanate, xylylenediisocyanate, dicyclohexylmethane diisocyanate, lysine diisocyanate ortetramethylxylylene diisocyanate, an alicyclic polyisocyanate such asisophorone diisocyanate, or a modified product thereof.

In some embodiments, a modified product of a polyisocyanate is aprepolymer modified product which is a reaction product of a lowmolecular weight diol with a low molecular weight triol, a buret productwhich is a reaction product with water, or a trimer having anisocyanurate skeleton.

The isocyanate group-terminated prepolymer can be produced by reacting astoichiometrically excess amount of a polyisocyanate to the polyolcomposition. It can be produced by thermally reacting the polyolcomposition with the polyisocyanate at a temperature of from 60 to 100°C. for from 1 to 30 hours in a dry nitrogen stream in the presence orabsence of a solvent and optionally in the presence of aurethane-forming catalyst.

In some embodiments, a urethane-forming catalyst is an organometalliccompound of tin, lead or titanium. In some embodiments aurethane-forming catalyst is an organic tin compound, such as dibutyltindilaurate, dibutyltin dioctoate or stannous octoate.

An isocyanate group-terminated prepolymer of the present invention canbe used for uses known in the art and familiar to the skilled artisan.In some embodiments, it can be used for a humidity curable compositionwhich is cured by a reaction with moisture in air, a two-part curablecomposition to be reacted with a curing agent such as a polyamine, apolyol or a low molecular weight polyol, a casting polyurethaneelastomer, or other applications.

The present invention also provides a polyurethane resin obtained byreacting the above polyol composition with a polyisocyanate. Such apolyurethane resin can be produced by a known method, and a curing agentsuch as a polyamine or a low molecular polyol, or the above mentionedurethane-forming catalyst may optionally be used.

In the production of polyurethanes, polyols of the invention may bereacted with the polyisocyanates using conventional techniques that havebeen fully described in the prior art. Depending upon whether theproduct is to be a homogeneous or microcellular elastomer, a flexible orrigid foam, an adhesive, coating or other form, the reaction mixture maycontain other conventional additives, such as chain-extenders, forexample 1,4-butanediol or hydrazine, catalysts, for example tertiaryamines or tin compounds, surfactants, for example siloxane-oxyalkylenecopolymers, blowing agents, for example water andtrichlorofluoromethane, cross-linking agents, for exampletriethanolamine, fillers, pigments, fire-retardants and the like.

To accelerate the reaction between the isocyanate-reactive groups of thepolyol resin and the isocyanate groups of the crosslinker, it ispossible to use known catalysts, for example, dibutyltin dilaurate,tin(II) octoate, 1,4-diazabicyclo[2.2.2]-octane, or amines such astriethylamine. These are typically used in an amount of from 10⁻⁵ to10⁻² g, based on the weight of the crosslinker.

The crosslinking density can be controlled by varying the functionalityof the polyisocyanate, the molar ratio of the polyisocyanate to thepolyol resin, or by additional use of monofunctional compounds reactivetoward isocyanate groups, such as monohydric alcohols, e.g. ethylhexanolor propylheptanol.

A crosslinker is generally used in an amount which corresponds to anNCO:OH equivalents ratio of from 0.5 to 2, preferably from 0.75 to 1.5and most preferably from 0.8 to 1.2.

Suitable crosslinking agents are also epoxy compounds having at leasttwo epoxide groups in the molecule, and their extension products formedby preliminary extension (prepolymers for epoxy resins, as described,for example in Ullmann's Encyclopedia of Industrial Chemistry, 6thedition, 2000, Electronic Release, in the chapter “Epoxy Resins”). Epoxycompounds having at least two epoxide groups in the molecule include, inparticular:

(i) Polyglycidyl and poly(β-methylglycidyl) esters which are obtainableby reacting a compound having at least two carboxyl groups, such as analiphatic or aromatic polycarboxylic acid, with epichlorohydrin orbeta-methylepichlorohydrin. The reaction is effected, preferably, in thepresence of a base. Suitable aliphatic polycarboxylic acids are oxalicacid, succinic acid, glutaric acid, adipic acid, pimelic acid, azelaicacid, dimerized or trimerized linolenic acid, tetrahydrophthalic acid,hexahydrophthalic acid or 4-methylhexahydrophthalic acid. Suitablearomatic polycarboxylic acids are, for example, phthalic acid,isophthalic acid or terephthalic acid.

(ii) Polyglycidyl or poly(β-methylglycidyl) ethers which derive, forexample, from acyclic alcohols, such as ethylene glycol, diethyleneglycol, poly(oxyethylene) glycols, propane-1,2-diol, poly(oxypropylene)glycols, propane-1,3-diol, butane-1,4-diol, poly(oxytetramethylene)glycols, pentane-1,5-diol, hexane-1,6-diol, hexane-2,4,6-triol,glycerol, 1,1,1-trimethylolpropane, pentaerythritol, sorbitol; or cyclicalcohols such as 1,4-cyclohexanedimethanol,bis(4-hydroxycyclohexyl)methane or 2,2-bis(4-hydroxycyclohexyl)propane;or comprise aromatic rings, such as N,N-bis(2-hydroxyethyl)aniline orp,p-bis(2-hydroxyethylamino)diphenylmethane. The glycidyl ethers mayalso derive from monocyclic phenols such as resorcinol or hydroquinone,or polycyclic phenols, such as bis(4-hydroxyphenyl)methane,4,4′-dihydroxybiphenyl, bis(4-hydroxyphenyl) sulfone,1,1,2,2-tetrakis(4-hydroxyphenyl)ethane,2,2-bis(4-hydroxyphenyl)propane,2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane, or from novolaks which areobtainable by condensing aldehydes, such as formaldehyde, acetaldehyde,chloral or furfural, with phenols, such as phenol, 4-chlorophenol,2-methylphenol, 4-tert-butylphenol or bisphenols.

(iii) Poly(N-glycidyl) compounds which are obtainable bydehydrochlorinating the reaction products of epichlorohydrin with amineswhich have at least two amine hydrogen atoms, such as aniline,n-butylamine, bis(4-aminophenyl)methane, m-xylylenediamine orbis(4-methylaminophenyl)methane. The poly(N-glycidyl) compounds alsoinclude triglycidyl isocyanurates, N,N′-diglycidyl derivatives ofalkyleneureas such as ethyleneurea or 1,3-propyleneurea, and thediglycidyl derivatives or hydantoins such as 5,5-dimethylhydantoin.

(iv) Poly(S-glycidyl) compounds such as di-S-glycidyl derivatives whichderive from dithiols, such as ethane-1,2-dithiol orbis(4-mercaptomethylphenyl) ether.

(v) Cycloaliphatic epoxy compounds such as bis(2,3-epoxycyclopentyl)ether, 2,3-epoxycyclopentyl glycidyl ether,1,2-bis(2,3-epoxycyclopentyloxy)ethane or 3,4-epoxycyclohexylmethyl3′,4′-epoxycyclohexanecarboxylate; or mixed cycloaliphatic-aliphaticepoxy compounds such as limonene diepoxide.

In some embodiments, the present disclosure encompasses higher polymersformed with polyol resins of the present invention that additionallycomprise a stiffening polymer which comprises (meth)acryloyl and/orvinylaromatic units. The stiffening is obtainable by free-radicallypolymerizing (meth)acrylic monomers or vinylaromatic monomers. Examplesof suitable monomers are styrene, ring-alkylated styrenes withpreferably C₁₋₄ alkyl radicals such as α-methylstyrene, p-methylstyrene,acrylonitrile, methacrylonitrile, acrylamide or methacrylamide, alkylacrylates and methacrylates having from 1 to 4 carbon atoms in the alkylradical, in particular methyl methacrylate. Preference is given to usingmonomers and monomer mixtures which give rise to a polymer or copolymerhaving a glass transition temperature of more than +20° C. andpreferably more than +50° C.

The stiffening polymer may, aside from (meth)acrylic monomers orvinylaromatic monomers, comprise various monomers. The (meth)acrylicmonomers or vinylaromatic monomers make up generally at least 20% byweight, preferably at least 50% by weight, in particular at least 70% byweight, of the constituent monomers.

The encompassed higher polymer compositions may additionally comprisecustomary assistants such as fillers, diluents or stabilizers.

Suitable fillers are, for example, silica, colloidal silica, calciumcarbonate, carbon black, titanium dioxide, mica and the like.

Suitable diluents are, for example, polybutene, liquid polybutadiene,hydrogenated polybutadiene, paraffin oil, naphthenenates, atacticpolypropylene, dialkyl phthalates, reactive diluents, for example,alcohols and oligoisobutenes.

Suitable stabilizers are, for example, 2-benzothiazolyl sulfide,benzothiazole, thiazole, dimethyl acetylenedicarboxylate, diethylacetylenedicarboxylate, BHT, butylhydroxyanisole, vitamin E.

Further higher polymeric materials which may be obtained from thepolyols of the invention include vinyl type polymers made bypolymerising ethylenically unsaturated derivatives of the polyols. Suchderivatives may be obtained, for example, by reacting the polyols withethylenically unsaturated carboxylic acids, for example acrylic,methacrylic and itaconic acids or ester-forming derivatives thereof.

Another useful method of forming ethylenically unsaturated derivativesof the polyols is to react said polyols with organic polyisocyanates,for example those mentioned above, and then to react the isocyanategroup terminated products obtained with hydroxyalkyl acrylates ormethacrylates, for example the 2-hydroxyethyl or 2-hydroxypropylcompounds. Alternatively, the polyols may be reacted withisocyanato-acrylates obtained by reacting a diisocyanate with ahydroxalkyl acrylate or methacrylate.

The ethylenically unsaturated derivatives of the fluorinated polyols maybe polymerized, preferably in the presence of co-monomers such asacrylonitrile, styrene, ethyl acrylate, butyl acrylate or methylmethacrylate, using conditions that have been fully described in theprior art for vinyl polymerisations. Useful molded plastics articles maybe made in this way.

Further higher polymeric materials which may be obtained from thepolyols of the invention include epoxy resins prepared in conventionalmanner from epoxy derivatives of the polyols. Such derivatives may beobtained, for example, by reacting the polyols with epichlorohydrin inthe presence of bases.

Articles of manufacture comprising provided polycarbonate polyol and/orpolyurethane compositions can be made using known methods and proceduresdescribed in the art. The skilled artisan, after reading the presentdisclosure, will be able to manufacture such articles using well knownprotocols and techniques.

Other Embodiments

The foregoing has been a description of certain non-limiting embodimentsof the invention. Accordingly, it is to be understood that theembodiments of the invention herein described are merely illustrative ofthe application of the principles of the invention. Reference herein todetails of the illustrated embodiments is not intended to limit thescope of the claims, which themselves recite those features regarded asessential to the invention.

1. A polymerization system for the copolymerization of CO₂ and epoxides,the system comprising: a metal complex including a permanent ligand setand at least one ligand that is a polymerization initiator, and a chaintransfer agent having one or more sites capable of initiatingcopolymerization of epoxides and CO₂, wherein the chain transfer agentcontains one or more masked hydroxyl groups.
 2. The polymerizationsystem of claim 1, wherein the chain transfer agent has a structureY-A-(Y)_(n′), wherein: each —Y group is independently a functional groupcapable of initiating chain growth of epoxide CO₂ copolymers or aprotected hydroxyl group, wherein at least one Y group is a protectedhydroxyl group and the number of Y protected hydroxyl groups is lessthan the total number of Y groups; -A- is a multivalent moiety; and n′is an integer between 1 and 10, inclusive.
 3. The polymerization systemof claim 2, wherein each Y group is independently selected from thegroup consisting of: —OR^(PG), —OH, —C(O)OH, —C(OR^(y))OH, —OC(R^(y))OH,—NHR^(y), —NHC(O)R^(y), —NHC═NR^(y); —NR^(y)C═NH; —NR^(y)C(NR^(y) ₂)═NH;—NHC(NR₂)═NR^(y); —NHC(O)OR^(y), —NHC(O)NR₂; —C(O)NHR^(y), —C(S)NHR^(y),—OC(O)NHR^(y), —OC(S)NHR^(y), —SH, —C(O)SH, —B(OR^(y))OH,—P(O)_(a)(R^(y))_(b)(OR^(y))_(c)(O)_(d)H,—OP(O)_(a)(R^(y))_(b)(OR^(y))_(c)(O)_(d)H, —N(R^(y))OH, —ON(R^(y))H;═NOH, ═NN(R^(y))H, wherein: each occurrence of R^(y) is independently—H, or an optionally substituted radical selected from the groupconsisting of C₁₋₂₀ aliphatic, C₁₋₂₀ heteroaliphatic, 3- to 12-memberedheterocyclic, and 6- to 12-membered aryl; each occurrence of R^(PG) isindependently a hydroxyl protecting group, wherein a single R^(PG)moiety may protect multiple hydroxyl groups; a and b are eachindependently 0 or 1; c is 0, 1 or 2; d is 0 or 1; and the sum of a, b,and c is 1 or 2 and where an acidic hydrogen atom bound in any of theabove functional groups may be replaced by a metal atom or an organiccation.
 4. The polymerization system of claim 3, wherein each Y group isindependently selected from the group consisting of —OR^(PG), —OH, and—C(O)OH.
 5. The polymerization system of claim 3, wherein each —OR^(PG)is selected from the group consisting of an aliphatic ether, asubstituted methyl ether, a cycloaliphatic ether, an arylalkyl ether, asilyl ether, a formate ester, an aliphatic ester, an aryl ester, acarbamate, a carbonate, an acetal, a ketal, a cyclic carbonate, and acyclic boronate.
 6. The polymerization system of claim 3, wherein -A- isan optionally substituted radical selected from the group consisting of:straight or branched C₂₋₃₀ aliphatic, straight or branched C₂₋₃₀heteroaliphatic, 6- to 12-membered aryl, 3- to 12-membered heterocyclic,5- to 12-membered heteroaryl, polyolefins, polyesters, polyethers,polycarbonates, polyoxymethylene and mixtures of two or more of these.7. The polymerization system of claim 2, wherein n′ is 1 to 4, orwherein n′ is 1, or wherein n′ is 2, or wherein n′ is 3, or wherein n′is
 4. 8. The polymerization system of claim 1, wherein the chaintransfer agent is a polyhydric alcohol, wherein one or more hydroxylgroups are protected.
 9. The polymerization system of claim 1, whereinthe chain transfer agent is a diol, wherein one hydroxyl group isprotected.
 10. The polymerization system of claim 9, wherein the diol isselected from the group consisting of: 1,2-ethanediol, 1,2-propanediol,1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol,1,5-pentanediol, 2,2-dimethylpropane-1,3-diol,2-butyl-2-ethylpropane-1,3-diol, 1,5-hexanediol, 1,6-hexanediol,1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol,2,2,4,4-tetramethylcyclobutane-1,3-diol, 1,3-cyclopentanediol,1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol,1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol,1,4-cyclohexanedimethanol, and 1,4-cyclohexanediethanol, or wherein thediol is selected from the group consisting of: diethylene glycol,triethylene glycol, tetraethylene glycol, higher poly(ethylene glycol)having number average molecular weights of from 220 to about 2000 g/mol,dipropylene glycol, tripropylene glycol, and higher poly(propyleneglycols) having number average molecular weights of from 234 to about2000 g/mol, or wherein the diol is selected from the group consistingof: 4,4′-(1-methylethylidene) bis[cyclohexanol],2,2′-methylenebis[phenol], 4,4′-methylenebis[phenol],4,4′-(phenylmethylene)bis [phenol], 4,4′-(diphenylmethylene)bis[phenol],4,4′-(1,2-ethanediyl)bis[phenol], 4,4′-(1,2-cyclohexanediyl)bis[phenol],4,4′-(1,3-cyclohexanediyl)bis[phenol],4,4′-(1,4-cyclohexanediyl)bis[phenol], 4,4′-ethylidenebis[phenol],4,4′-(1-phenylethylidene)bis[phenol], 4,4′-propylidenebis[phenol],4,4′-cyclohexylidenebis [phenol], 4,4′-(1-methylethylidene)bis[phenol],4,4′-(1-methylpropylidene)bis[phenol],4,4′-(1-ethylpropylidene)bis[phenol], 4,4′-cyclohexylidenebis[phenol],4,4′-(2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diyldi-2,1-ethanediyl)bis[phenol], 1,2-benzenedimethanol, 1,3-benzenedimethanol,1,4-benzenedimethanol,4,4′-[1,3-phenylenebis(1-methylethylidene)]bis[phenol],4,4′-[1,4-phenylenebis(1-methylethylidene)]bis[phenol], phenolphthalein,4,4′-(1-methylidene)bis[2-methylphenol],4,4′-(1-methylethylidene)bis[2-(1-methylethyl)phenol], and2,2′-methylenebis[4-methyl-6-(1-methylethyl)phenol], or wherein the diolis selected from the group consisting of: 1,3 propane diol, 1,4 butanediol, dipropylene glycol, and diethylene glycol.
 11. The polymerizationsystem of claim 1, wherein the chain transfer agent is a hydroxy acid,wherein at least one hydroxyl group of the hydroxy acid is protected.12. The polymerization system of claim 11, wherein the hydroxy acid isan alpha-hydroxy acid, or wherein the hydroxy acid is selected from thegroup consisting of: glycolic acid, DL-lactic acid, D-lactic acid,L-lactic, citric acid and mandelic acid, or wherein the hydroxy acid isa beta-hydroxy acid, or wherein the hydroxy acid is selected from thegroup consisting of: 3-hydroxypropionic acid, DL 3-hydroxybutryic acid,D-3 hydroxybutryic acid, L 3-hydroxybutyric acid, DL-3-hydroxy valericacid, D-3-hydroxy valeric acid, L-3-hydroxy valeric acid, salicylicacid, and derivatives of salicylic acid, or wherein the hydroxy acid isa α-ω hydroxy acid, or wherein the hydroxy acid is selected from thegroup consisting of: of optionally substituted C₃₋₂₀ aliphatic α-ωhydroxy acids and polyester oligomeric esters, or wherein the hydroxyacid is selected from the group consisting of:

where each R^(PG) is independently the hydroxyl protecting group. 13.The polymerization system of claim 1, wherein the metal complex has theformula L_(p)-M-(L_(I))_(n), where L_(p) is a permanent ligand set, M isa metal atom, L_(I) is a ligand that is a polymerization initiator, andn is an integer between 0 and 2, inclusive, representing the number ofinitiating ligands present; and wherein M is selected from the groupconsisting of Cr, Mn, V, Fe, Co, Mo, W, Ru, Al, and Ni, or wherein M isCr, or wherein M is Mn, or wherein M is Co.
 14. The polymerizationsystem of claim 13 wherein the L_(p)-M moiety of the metal complex has aformula selected from the group consisting of:

wherein, Q, at each occurrence is independently O or S; R¹ and R^(1′)are independently selected from the group consisting of: —H, optionallysubstituted C₁ to C₁₂ aliphatic; optionally substituted 3- to14-membered carbocycle; optionally substituted 3- to 14-memberedheterocycle; and R²¹; R² and R^(2′) are independently selected from thegroup consisting of: —H; optionally substituted C₁ to C₁₂ aliphatic;optionally substituted 3- to 14-membered carbocycle; optionallysubstituted 3- to 14-membered heterocycle; R¹⁴; R²⁰; and R²¹; R³, andR^(3′) are independently selected from the group consisting of: —H;optionally substituted C₁ to C₁₂ aliphatic; optionally substituted 3- to14-membered carbocycle; optionally substituted 3- to 14-memberedheterocycle, and R²¹; R^(c) at each occurrence is independently selectedfrom the group consisting of: —H; optionally substituted C₁ to C₁₂aliphatic; an optionally substituted 3- to 14-membered carbocycle; anoptionally substituted 3- to 14 membered heterocycle; R²⁰; and R²¹,where two or more R^(c) groups may be taken together with interveningatoms to form one or more optionally substituted rings and, when twoR^(c) groups are attached to the same carbon atom, they may be takentogether along with the carbon atom to which they are attached to form amoiety selected from the group consisting of: an optionally substituted3- to 8-membered spirocyclic ring, a carbonyl, an oxime, a hydrazone,and an imine; R^(d) at each occurrence is independently selected fromthe group consisting of: optionally substituted C₁ to C₁₂ aliphatic;optionally substituted 3- to 14-membered carbocycle; optionallysubstituted 3- to 14-membered heterocycle; R²⁰; and R²¹, where two ormore R^(d) groups may be taken together with intervening atoms to formone or more optionally substituted rings; and

represents an optionally substituted moiety covalently linking twonitrogen atoms, where any of [R^(2′) and R^(3′)], [R² and R³], [R¹ andR²], and [R^(1′) and R^(2′)] may optionally be taken together withintervening atoms to form one or more rings which may in turn besubstituted with one or more groups selected from R¹⁴; R²⁰; and R²¹; andwhere R¹⁴ at each occurrence is independently selected from the groupconsisting of: a

(Z)_(p) group; halogen; optionally substituted C₁ to C₁₂ aliphatic;optionally substituted 3- to 14-membered carbocycle; optionallysubstituted 3- to 14-membered heterocycle; —OR¹⁰; —OC(O)R¹³; —OC(O)OR¹³;—OC(O)NR¹¹R¹²; —CN; —CNO; —C(R¹³)_(z)H_((3-z)); —C(O)R¹³; —C(O)OR¹³;—C(O)NR¹¹R¹²; —NR¹¹R¹²; —NR¹¹C(O)R¹³; —NR¹¹C(O)OR¹³; —NR¹¹SO₂R¹³;—N⁺R¹¹R¹²R¹³ X⁻; —P⁺(R¹¹)₃ X⁻; —P(R¹¹)₃═N⁺═P(R¹¹)₃ X⁻; —As⁺R¹¹R¹²R¹³ X⁻;—NCO; —N₃; —NO₂; —S(O)_(x)R¹³; and —SO₂NR¹¹R¹²; R²⁰ at each occurrenceis independently selected from the group consisting of: a

(Z)_(p) group; halogen; —OR¹⁰; —OC(O)R¹³; —OC(O)OR¹³; —N⁺(R¹¹)₃ X⁻;—P⁺(R¹¹)₃ X⁻; —P(R¹¹)₃═N═P(R¹¹)₃ X⁻; —As⁺R¹¹R¹²R¹³ X⁻; —OC(O)NR¹¹R¹²;—CN; —CNO; —C(O)R¹³; —C(O)OR¹³; —C(O)NR¹¹R¹²; —C(R¹³)_(z)H_((3-z));—NR¹¹R¹²; —NR¹¹C(O)R¹³; —NR¹¹C(O)OR¹³; —NCO; —NR¹¹SO₂R¹³; —S(O)_(x)R¹³;—S(O)₂NR¹¹R¹²; —NO₂; —N₃; and —Si(R¹³)_((3-z))[(CH₂)_(k)R¹⁴]_(z); R²¹ ateach occurrence is independently selected from the group consisting of:a

(Z)_(p) group; —(CH₂)_(k)R²⁰; —(CH₂)_(k)—Z—(CH₂)_(k)R²⁰;—C(R¹⁷)_(z)H_((3-z)); —(CH₂)_(k)C(R¹⁷)_(z)H_((3-z));—(CH₂)_(m)—Z—(CH₂)_(m)C(R¹⁷)_(z)H_((3-z)); —(CH₂)_(k)—Z—R¹⁶; X⁻ is anyanion; Z is a divalent linker selected from the group consisting of—(CH═CH)_(a)—; —(CH≡CH)_(a)—; —C(O)—; —C(═NOR¹¹)—; —C(═NNR¹¹R¹²)—; —O—;—OC(O)—; —C(O)O—; —OC(O)O—; —N(R¹¹)—; —N(C(O)R¹³)—; —C(O)NR¹³—;—N(C(O)R¹³)O—; —NR¹³C(O)R¹³N—; —S(O)_(x)—; a polyether; and a polyamine;R¹⁰ at each occurrence is independently selected from the groupconsisting of: —H; optionally substituted C₁₋₁₂ aliphatic; an optionallysubstituted 3- to 14-membered carbocycle; an optionally substituted 3-to 14-membered heterocycle —S(O)₂R¹³; —Si(R¹⁵)₃; —C(O)R¹³; and ahydroxyl protecting group; R¹¹ and R¹² at each occurrence areindependently selected from the group consisting of: —H; optionallysubstituted C₁ to C₁₂ aliphatic; an optionally substituted 3- to14-membered carbocycle; an optionally substituted 3- to 14-memberedheterocycle; where two or more R¹ or R¹² groups can optionally be takentogether with intervening atoms to form an optionally substituted 3- to10-membered ring; R¹³ at each occurrence is independently selected fromthe group consisting of: —H; optionally substituted C₁ to C₁₂ aliphatic;an optionally substituted 3- to 14-membered carbocycle; and optionallysubstituted 3- to 14-membered heterocycle, where two or more R¹³ groupson the same molecule may optionally be taken together to form ring; R¹⁵at each occurrence is independently selected from the group consistingof: optionally substituted C₁₋₁₂ aliphatic, an optionally substituted 3-to 14-membered carbocycle; and an optionally substituted 3- to14-membered heterocycle; R¹⁶ at each occurrence is independentlyselected from the group consisting of: optionally substituted C₁-C₁₂aliphatic, an optionally substituted 3- to 14-membered carbocycle; anoptionally substituted 3- to 14-membered heterocycle; and—C(R¹⁷)_(z)H_((3-z)); R¹⁷ at each occurrence is independently selectedfrom the group consisting of: —H; optionally substituted C₁ to C₁₂aliphatic; an optionally substituted 3- to 14-membered carbocycle; andoptionally substituted 3-to 14-membered heterocycle; each

(Z)_(p) group comprises a covalent linker “

” containing one or more atoms selected from the group consisting of C,O, N, S, and Si; “Z” is an activating functional group havingco-catalytic activity in epoxide CO₂ copolymerization, and p is aninteger from 1 to 4 indicating the number of individual activatingfunctional groups Z present on a given

(Z)_(p) group; a is 1, 2, 3, or 4; k is independently at each occurrencean integer from 1 to 8 inclusive; m is 0 or an integer from 1 to 8inclusive; x is 0, 1, or 2; and z is 1, 2, or
 3. 15. The polymerizationsystem of claim 13, wherein L_(p)-M-(L_(I))_(n) has a formula selectedfrom the group consisting of:

wherein: R^(4a), R^(4a′), R^(5a), R^(5a′), R^(6a), R^(6a′), R^(7a), andR^(7a′) are each independently hydrogen, a

(Z)_(p) group, halogen, —NO₂, —CN, —SR¹³, —S(O)R¹³, —S(O)₂R¹³,—NR¹¹C(O)R¹³, —OC(O)R¹³, —CO₂R¹³, —NCO, —N₃, —OR¹⁰, —OC(O)NR¹¹R¹²,—Si(R¹³)₃, —NR¹¹R¹², —NR¹¹C(O)R¹³, and —NR¹¹C(O)OR¹³; or an optionallysubstituted radical selected from the group consisting of C₁₋₂₀aliphatic; C₁₋₂₀ heteroaliphatic; 6- to 10-membered aryl; 5- to10-membered heteroaryl; and 3- to 7-membered heterocyclic, where [R^(1a)and R^(4a)], [R^(1a′)and R^(4a′)] and any two adjacent R^(4a), R^(4a′),R^(5a), R^(5a′), R^(6a), R^(6a′), R^(7a), and R^(7a′) groups can betaken together with intervening atoms to form one or more optionallysubstituted rings optionally containing one or more heteroatoms; R^(1a)and R^(1a′) are hydrogen when not taken together with R^(4a) andR^(4a′); R^(c) at each occurrence is independently selected from thegroup consisting of: —H: optionally substituted C₁ to C₁₂ aliphatic; anoptionally substituted 3- to 14-membered carbocycle; an optionallysubstituted 3- to 14 membered heterocycle; R²⁰; and R²¹, where two ormore R^(c) groups may be taken together with intervening atoms to formone or more optionally substituted rings and, when two R^(c) groups areattached to the same carbon atom, they may be taken together along withthe carbon atom to which they are attached to form a moiety selectedfrom the group consisting of: an optionally substituted 3- to 8-memberedspirocyclic ring, a carbonyl, an oxime, a hydrazone, and an imine; R¹⁰at each occurrence is independently selected from the group consistingof: —H: optionally substituted C₁₋₁₂ aliphatic; an optionallysubstituted 3- to 14-membered carbocycle; an optionally substituted 3-to 14-membered heterocycle —S(O)₂R¹³; —Si(R¹⁵)₃; —C(O)R¹³; and ahydroxyl protecting group; R¹¹ and R¹² at each occurrence areindependently selected from the group consisting of: —H: optionallysubstituted C₁ to C₁₂ aliphatic; an optionally substituted 3- to14-membered carbocycle; an optionally substituted 3- to 14-memberedheterocycle; where two or more R¹¹ or R¹² groups can optionally be takentogether with intervening atoms to form an optionally substituted 3- to10-membered ring: R¹³ at each occurrence is independently selected fromthe group consisting of: —H: optionally substituted C₁ to C₁₂ aliphatic;an optionally substituted 3- to 14-membered carbocycle; and optionallysubstituted 3- to 14-membered heterocycle, where two or more R¹³ groupson the same molecule may optionally be taken together to form ring: R¹⁴at each occurrence is independently selected from the group consistingof: a

(Z)_(p) group; halogen: optionally substituted C₁ to C₂ aliphaticoptionally substituted 3- to 14-membered carbocycle; optionallysubstituted 3- to 14-membered heterocycle; —OR¹⁰; —OC(O)R¹³; —OC(O)OR¹³;—OC(O)NR¹¹R¹²; —CN; —CNO; —C(R¹³)_(Z)H_((3-z)); —C(O)R¹³; —C(O)OR¹³;—C(O)NR¹¹R¹²; —NR¹¹R¹²; —NR₁₁C(O)R¹³; —NR¹¹C(O)OR¹³; —NR¹¹SO₂R¹³;—N⁺R¹¹R¹²R¹³ X⁻; —P(R¹¹)₃ X⁻; —P(R¹¹)₃═N⁺═P(R¹¹)₃ X⁻; —As⁺R¹¹R¹²R¹³ X⁻;—NCO; —N₃; —NO₂; —S(O)_(x)R¹³; and —SO₂NR¹¹R¹²; R¹⁵ at each occurrenceis independently selected from the group consisting of: optionallysubstituted C₁₋₁₂ aliphatic, an optionally substituted 3- to 14-memberedcarbocycle; and an optionally substituted 3- to 14-membered heterocycle;R¹⁶ at each occurrence is independently selected from the groupconsisting of: optionally substituted C₁-C₁₂ aliphatic, an optionallysubstituted 3- to 14-membered carbocycle; an optionally substituted 3-to 14-membered heterocycle; and —C(R¹⁷)_(z)H_((3-z)); R¹⁷ at eachoccurrence is independently selected from the group consisting of: —H:optionally substituted C₁ to C₁₂ aliphatic; an optionally substituted 3-to 14-membered carbocycle; and optionally substituted 3-to 14-memberedheterocycle; R²⁰ at each occurrence is independently selected from thegroup consisting of: a

(Z)_(p) group; halogen; —OR¹⁰; —OC(O)R¹³; —OC(O)OR¹³; —N(R¹¹)₃ X⁻;—P⁺(R¹¹)₃ X⁻; —P(R¹¹)₃═N⁺═P(R¹¹)₃ X⁻; —As⁺R¹¹R¹²R¹³ X⁻; —OC(O)NR¹¹R¹²;—CN; —CNO; —C(O)R¹³; —C(O)OR¹³; —C(O)NR¹¹R¹²; —C(R¹³)_(z)H_((3-z));—NR¹¹R¹²; —NR¹¹C(O)R¹³; —NR¹¹C(O)OR¹³; —NCO; —NR¹¹SO₂R¹³; —S(O)R¹³;—S(O)₂NR¹¹R¹²; —NO₂; —N₃; and —Si(R¹³)_((3-z))[(CH₂)_(k)R¹⁴]_(z); R²¹ ateach occurrence is independently selected from the group consisting of:a

(Z)_(p) group; —(CH₂)_(k)R²⁰; —(CH₂)_(k)—Z—(CH₂)_(k)R²⁰;—C(R¹⁷)_(z)H_((3-z)); —(CH₂)_(k)C(R¹⁷)_(z)H_((3-z));—(CH₂)_(m)—Z—(CH₂)_(m)C(R¹⁷)_(z)H_((3-z)); —(CH₂)_(k)—Z—R¹⁶; X⁻ is anyanion; Z is a divalent linker selected from the group consisting of—(CH═CH)_(a)—; —(CH≡CH)_(a)—; —C(O)—; —C(═NOR¹¹)—; —C(═NNR¹¹R¹²)—; —O—;—OC(O)—; —C(O)O—; —OC(O)O—; —N(R¹¹)—; —N(C(O)R¹³)—; —C(O)NR¹³—;—N(C(O)R¹³)O—; —NR¹³C(O)R¹³N—; —S(O)_(x)—; a polyether; and a polyamine;each

(Z)_(p) group comprises a covalent linker “

” containing one or more atoms selected from the group consisting of C,O, N, S, and Si; “Z” is an activating functional group havingco-catalytic activity in epoxide CO₂ copolymerization, and p is aninteger from 1 to 4 indicating the number of individual activatingfunctional groups Z present on a given

(Z)_(p) group; a is 1, 2, 3, or 4; k is independently at each occurrencean integer from 1 to 8 inclusive; m is 0 or an integer from 1 to 8inclusive; x is 0, 1, or 2; z is 1, 2, or 3; R′ is R^(d) or a

(Z)_(p) group, where two or more adjacent R′ groups can be takentogether to form an optionally substituted saturated, partiallyunsaturated, or aromatic 3- to 12-membered ring containing 0 to 4heteroatoms; and R^(d) is selected from the group consisting of:optionally substituted C₁ to C₁₂ aliphatic; optionally substituted 3- to14-membered carbocycle; optionally substituted 3- to 14-memberedheterocycle; R²⁰; and R²¹; or wherein L_(p)-M-(L_(I))_(n) has a formulaselected from the group consisting of:


16. The polymerization system of claim 15, wherein -M- is cobalt. 17.The polymerization system of claim 1, wherein the chain transfer agentis present in a molar ratio of at least 100:1 relative to the metalcomplex, or wherein the chain transfer agent is present in a molar ratioof at least 1000:1 relative to the metal complex, or wherein the chaintransfer agent is present in a molar ratio of between about 10:1 andabout 10000:1 relative to the metal complex, or wherein the chaintransfer agent is present in a molar ratio of between about 50:1 andabout 5000:1 relative to the metal complex, or wherein the chaintransfer agent is present in a molar ratio of between about 50:1 andabout 1000:1 relative to the metal complex, or wherein the chaintransfer agent is present in a molar ratio of between about 20:1 andabout 500:1 relative to the metal complex, or wherein the chain transferagent is present in a molar ratio of between about 100:1 and about 250:1relative to the metal complex.
 18. The polymerization system of claim 1,wherein at least one of the masked hydroxyl groups is a latent hydroxylgroup.
 19. The polymerization system of claim 1, wherein the chaintransfer agent comprises a benzylic alcohol functionality.
 20. Thepolymerization system of claim 1, wherein the chain transfer agent isselected from the group consisting of methanol, t-butanol, allylalcohol, and benzyl alcohol. 21-28. (canceled)
 29. A polycarbonatepolyol composition comprising an epoxide CO₂ copolymer characterized inthat the copolymer has: an Mn between about 400 and about 20,000,greater than 90% carbonate linkages, at least 90% of the end groups arehydroxyl groups; wherein substantially all polycarbonate chains havinghydroxyl end groups have no embedded chain transfer agent. 30-31.(canceled)
 32. A polyurethane composition formed by reaction of one ormore isocyanates with one or more aliphatic polycarbonate polyols ofclaim
 29. 33. An article of manufacture comprising the polycarbonatepolyol composition of claim
 29. 34. (canceled)